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Section 4.7
                             Antiderivatives

                            V63.0121.006/016, Calculus I

                                   New York University


                                    April 8, 2010



    Announcements

         Quiz April 16 on §§4.1–4.4
         Final Exam: Monday, May 10, 10:00am

    .
.
Image credit: Ian Hampton
                                                         .   .   .   .   .   .
Announcements




    Quiz April 16 on §§4.1–4.4
    Final Exam: Monday, May 10, 10:00am




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 V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       2 / 32
Outline


What is an antiderivative?

Tabulating Antiderivatives
   Power functions
   Combinations
   Exponential functions
   Trigonometric functions

Finding Antiderivatives Graphically

Rectilinear motion


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  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       3 / 32
Objectives


      Given an expression for
      function f, find a
      differentiable function F
      such that F′ = f (F is called
      an antiderivative for f).
      Given the graph of a
      function f, find a
      differentiable function F
      such that F′ = f
      Use antiderivatives to
      solve problems in
      rectilinear motion


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  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       4 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.




                                                             .   .   .    .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???




                                                             .   .   .    .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???

Example
is F(x) = x ln x − x an antiderivative for f(x) = ln x?




                                                             .   .   .    .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???

Example
is F(x) = x ln x − x an antiderivative for f(x) = ln x?

Solution

                    d
                       (x ln x − x)
                    dx

                                                                    .   .   .    .       .      .

  V63.0121, Calculus I (NYU)          Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???

Example
is F(x) = x ln x − x an antiderivative for f(x) = ln x?

Solution

                    d                               1
                       (x ln x − x) = 1 · ln x + x · − 1
                    dx                              x

                                                                .   .   .    .       .      .

  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???

Example
is F(x) = x ln x − x an antiderivative for f(x) = ln x?

Solution

                    d                               1
                       (x ln x − x) = 1 · ln x + x · − 1 = ln x
                    dx                              x

                                                                .   .   .    .       .      .

  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Hard problem, easy check

Example
Find an antiderivative for f(x) = ln x.

Solution
???

Example
is F(x) = x ln x − x an antiderivative for f(x) = ln x?

Solution

                    d
                    dx
                                                    1
                       (x ln x − x) = 1 · ln x + x · − 1 = ln x
                                                    x
                                                                        
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  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010       5 / 32
Why the MVT is the MITC
Most Important Theorem In Calculus!



Theorem
Let f′ = 0 on an interval (a, b). Then f is constant on (a, b).

Proof.
Pick any points x and y in (a, b) with x  y. Then f is continuous on
[x, y] and differentiable on (x, y). By MVT there exists a point z in (x, y)
such that
                  f(y) − f(x)
                              = f′ (z) =⇒ f(y) = f(x) + f′ (z)(y − x)
                     y−x

But f′ (z) = 0, so f(y) = f(x). Since this is true for all x and y in (a, b),
then f is constant.

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   V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010       6 / 32
When two functions have the same derivative


Theorem
Suppose f and g are two differentiable functions on (a, b) with f′ = g′ .
Then f and g differ by a constant. That is, there exists a constant C
such that f(x) = g(x) + C.

Proof.

     Let h(x) = f(x) − g(x)
     Then h′ (x) = f′ (x) − g′ (x) = 0 on (a, b)
     So h(x) = C, a constant
     This means f(x) − g(x) = C on (a, b)



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  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       7 / 32
Outline


What is an antiderivative?

Tabulating Antiderivatives
   Power functions
   Combinations
   Exponential functions
   Trigonometric functions

Finding Antiderivatives Graphically

Rectilinear motion


                                                             .   .   .    .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010       8 / 32
Antiderivatives of power functions


                                                                y
                                                                .
                                                                                .(x) = x2
                                                                                f
 Recall that the derivative of a
 power function is a power
 function.
 Fact (The Power Rule)
 If f(x) = xr , then f′ (x) = rxr−1 .

                                                                    .
                                                                                x
                                                                                .




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  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives                   April 8, 2010       9 / 32
Antiderivatives of power functions

                                                                   ′
                                                                y f
                                                                . . (x) = 2x
                                                                               .(x) = x2
                                                                               f
 Recall that the derivative of a
 power function is a power
 function.
 Fact (The Power Rule)
 If f(x) = xr , then f′ (x) = rxr−1 .

                                                                 .
                                                                               x
                                                                               .




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  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives                  April 8, 2010       9 / 32
Antiderivatives of power functions

                                                                   ′
                                                                y f
                                                                . . (x) = 2x
                                                                               .(x) = x2
                                                                               f
 Recall that the derivative of a
 power function is a power
 function.                                                                     F
                                                                               . (x) = ?

 Fact (The Power Rule)
 If f(x) = xr , then f′ (x) = rxr−1 .

                                                                 .
                                                                               x
                                                                               .




                                                                 .   .    .     .       .      .

  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives                  April 8, 2010       9 / 32
Antiderivatives of power functions

                                                                   ′
                                                                y f
                                                                . . (x) = 2x
                                                                               .(x) = x2
                                                                               f
 Recall that the derivative of a
 power function is a power
 function.                                                                     F
                                                                               . (x) = ?

 Fact (The Power Rule)
 If f(x) = xr , then f′ (x) = rxr−1 .

 So in looking for antiderivatives
                                                                 .
 of power functions, try power                                                 x
                                                                               .
 functions!




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  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives                  April 8, 2010       9 / 32
Example
Find an antiderivative for the function f(x) = x3 .




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .

     r − 1 = 3 =⇒ r = 4




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4
                1 4
     So F(x) = x is an antiderivative.
                4




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4
                1 4
     So F(x) = x is an antiderivative.
                4
     Check:                 (    )
                        d 1 4           1
                               x = 4 · x4−1 = x3
                       dx 4             4




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4
                1 4
     So F(x) = x is an antiderivative.
                4
     Check:                 (    )
                        d 1 4
                       dx 4
                                        1
                               x = 4 · x4−1 = x3
                                        4
                                                                 

                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4
                1 4
     So F(x) = x is an antiderivative.
                4
     Check:                 (    )
                        d 1 4
                       dx 4
                                        1
                               x = 4 · x4−1 = x3
                                        4
                                                                 
     Any others?

                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Example
Find an antiderivative for the function f(x) = x3 .

Solution

     Try a power function F(x) = axr
     Then F′ (x) = arxr−1 , so we want arxr−1 = x3 .
                                                 1
     r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = .
                                                 4
                1 4
     So F(x) = x is an antiderivative.
                4
     Check:                 (    )
                        d 1 4
                       dx 4
                                        1
                               x = 4 · x4−1 = x3
                                        4
                                                                 
                                  1 4
     Any others? Yes, F(x) =        x + C is the most general form.
                                  4
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  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   10 / 32
Fact (The Power Rule for antiderivatives)
If f(x) = xr , then
                                            1 r+1
                               F(x) =          x
                                           r+1
is an antiderivative for f…




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  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   11 / 32
Fact (The Power Rule for antiderivatives)
If f(x) = xr , then
                                         1 r+1
                               F(x) =       x
                                      r+1
is an antiderivative for f as long as r ̸= −1.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   11 / 32
Fact (The Power Rule for antiderivatives)
If f(x) = xr , then
                                         1 r+1
                                  F(x) =    x
                                      r+1
is an antiderivative for f as long as r ̸= −1.

Fact
                       1
If f(x) = x−1 =          , then
                       x
                                  F(x) = ln |x| + C
is an antiderivative for f.




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  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010   11 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.




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  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                   {
                                                       ln(x)  if x  0;
                               F(x) = ln |x| =
                                                       ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                        ln |x|
                                     dx




                                                                       .   .   .     .       .     .

  V63.0121, Calculus I (NYU)             Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d           d
                                        ln |x| =    ln(x)
                                     dx          dx




                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d           d          1
                                        ln |x| =    ln(x) =
                                     dx          dx         x




                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          




                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d
                             ln |x|
                          dx


                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d           d
                             ln |x| =    ln(−x)
                          dx          dx


                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d           d           1
                             ln |x| =    ln(−x) =    · (−1)
                          dx          dx          −x


                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d           d           1           1
                             ln |x| =    ln(−x) =    · (−1) =
                          dx          dx          −x          x


                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d
                          dx
                             ln |x| =
                                      d
                                      dx
                                         ln(−x) =
                                                  1
                                                  −x
                                                     · (−1) =
                                                              1
                                                              x
                                                                                  

                                                                      .   .   .       .     .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
What's with the absolute value?
                                                  {
                                                      ln(x)  if x  0;
                               F(x) = ln |x| =
                                                      ln(−x) if x  0.

     The domain of F is all nonzero numbers, while ln x is only defined
     on positive numbers.
     If x  0,
                                     d
                                     dx
                                        ln |x| =
                                                 d
                                                 dx
                                                    ln(x) =
                                                            1
                                                            x
                                                                          
     If x  0,
                          d
                          dx
                             ln |x| =
                                      d
                                      dx
                                         ln(−x) =
                                                  1
                                                  −x
                                                     · (−1) =
                                                              1
                                                              x
                                                                                  
     We prefer the antiderivative with the larger domain.
                                                                      .   .   .       .     .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   12 / 32
Graph of ln |x|

                               y
                               .




                                   .                                 f
                                                                     .(x) = 1/x
                                                                     x
                                                                     .




                                                             .   .    .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                April 8, 2010   13 / 32
Graph of ln |x|

                               y
                               .




                                                                     F
                                                                     . (x) = ln(x)


                                   .                                 f
                                                                     .(x) = 1/x
                                                                     x
                                                                     .




                                                             .   .    .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                April 8, 2010   13 / 32
Graph of ln |x|

                               y
                               .




                                                                     . (x) = ln |x|
                                                                     F


                                   .                                 f
                                                                     .(x) = 1/x
                                                                     x
                                                                     .




                                                             .   .    .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                April 8, 2010   13 / 32
Combinations of antiderivatives
Fact (Sum and Constant Multiple Rule for Antiderivatives)

     If F is an antiderivative of f and G is an antiderivative of g, then
     F + G is an antiderivative of f + g.
     If F is an antiderivative of f and c is a constant, then cF is an
     antiderivative of cf.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   14 / 32
Combinations of antiderivatives
Fact (Sum and Constant Multiple Rule for Antiderivatives)

     If F is an antiderivative of f and G is an antiderivative of g, then
     F + G is an antiderivative of f + g.
     If F is an antiderivative of f and c is a constant, then cF is an
     antiderivative of cf.

Proof.
These follow from the sum and constant multiple rule for derivatives:
     If F′ = f and G′ = g, then

                               (F + G)′ = F′ + G′ = f + g

     Or, if F′ = f,
                                     (cF)′ = cF′ = cf
                                                                .   .   .     .       .     .

  V63.0121, Calculus I (NYU)      Section 4.7 Antiderivatives               April 8, 2010   14 / 32
Antiderivatives of Polynomials

Example
Find an antiderivative for f(x) = 16x + 5.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   15 / 32
Antiderivatives of Polynomials
Example
Find an antiderivative for f(x) = 16x + 5.

Solution
                         1 2
The expression             x is an antiderivative for x, and x is an antiderivative
                         2
for 1. So
                                 (         )
                                     1 2
                  F(x) = 16 ·          x       + 5 · x + C = 8x2 + 5x + C
                                     2

is the antiderivative of f.




                                                                    .   .   .     .       .     .

  V63.0121, Calculus I (NYU)          Section 4.7 Antiderivatives               April 8, 2010   15 / 32
Antiderivatives of Polynomials
Example
Find an antiderivative for f(x) = 16x + 5.

Solution
                         1 2
The expression             x is an antiderivative for x, and x is an antiderivative
                         2
for 1. So
                                 (         )
                                     1 2
                  F(x) = 16 ·          x       + 5 · x + C = 8x2 + 5x + C
                                     2

is the antiderivative of f.

Question
Why do we not need two C’s?

                                                                    .   .   .     .       .     .

  V63.0121, Calculus I (NYU)          Section 4.7 Antiderivatives               April 8, 2010   15 / 32
Antiderivatives of Polynomials

Example
Find an antiderivative for f(x) = 16x + 5.

Solution
                                (         )
                                    1 2
                  F(x) = 16 ·         x       + 5 · x + C = 8x2 + 5x + C
                                    2


Question
Why do we not need two C’s?

Answer
A combination of two arbitrary constants is still an arbitrary constant.
                                                                   .   .   .     .       .     .

  V63.0121, Calculus I (NYU)         Section 4.7 Antiderivatives               April 8, 2010   15 / 32
Exponential Functions

Fact
If f(x) = ax , f′ (x) = (ln a)ax .




                                                                   .   .   .     .       .     .

   V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   16 / 32
Exponential Functions

Fact
If f(x) = ax , f′ (x) = (ln a)ax .

Accordingly,
Fact
                                 1 x
If f(x) = ax , then F(x) =           a + C is the antiderivative of f.
                                ln a




                                                                   .   .   .     .       .     .

   V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   16 / 32
Exponential Functions

Fact
If f(x) = ax , f′ (x) = (ln a)ax .

Accordingly,
Fact
                                 1 x
If f(x) = ax , then F(x) =           a + C is the antiderivative of f.
                                ln a

Proof.
Check it yourself.




                                                                   .   .   .     .       .     .

   V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   16 / 32
Exponential Functions

Fact
If f(x) = ax , f′ (x) = (ln a)ax .

Accordingly,
Fact
                                 1 x
If f(x) = ax , then F(x) =           a + C is the antiderivative of f.
                                ln a

Proof.
Check it yourself.

In particular,
Fact
If f(x) = ex , then F(x) = ex + C is the antiderivative of f.
                                                                   .   .   .     .       .     .

   V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   16 / 32
Logarithmic functions?

     Remember we found

                                  F(x) = x ln x − x

     is an antiderivative of f(x) = ln x.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   17 / 32
Logarithmic functions?

     Remember we found

                                  F(x) = x ln x − x

     is an antiderivative of f(x) = ln x.
     This is not obvious. See Calc II for the full story.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   17 / 32
Logarithmic functions?

     Remember we found

                                           F(x) = x ln x − x

     is an antiderivative of f(x) = ln x.
     This is not obvious. See Calc II for the full story.
                                            ln x
     However, using the fact that loga x =       , we get:
                                            ln a

Fact
If f(x) = loga (x)

                                1                                  1
                F(x) =              (x ln x − x) + C = x loga x −      x+C
                               ln a                               ln a
is the antiderivative of f(x).
                                                                      .   .   .     .       .     .

  V63.0121, Calculus I (NYU)            Section 4.7 Antiderivatives               April 8, 2010   17 / 32
Trigonometric functions


Fact

                         d                          d
                            sin x = cos x              cos x = − sin x
                         dx                         dx




                                                                  .   .   .     .       .     .

  V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   18 / 32
Trigonometric functions


Fact

                         d                          d
                            sin x = cos x              cos x = − sin x
                         dx                         dx

So to turn these around,
Fact

     The function F(x) = − cos x + C is the antiderivative of f(x) = sin x.




                                                                  .   .   .     .       .     .

  V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   18 / 32
Trigonometric functions


Fact

                         d                          d
                            sin x = cos x              cos x = − sin x
                         dx                         dx

So to turn these around,
Fact

     The function F(x) = − cos x + C is the antiderivative of f(x) = sin x.
     The function F(x) = sin x + C is the antiderivative of f(x) = cos x.




                                                                  .   .   .     .       .     .

  V63.0121, Calculus I (NYU)        Section 4.7 Antiderivatives               April 8, 2010   18 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).

Check

             d      1    d
                =      ·   sec x
             dx   sec x dx


                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).

Check

             d      1    d           1
                =      ·   sec x =       · sec x tan x
             dx   sec x dx         sec x


                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).

Check

             d      1    d           1
                =      ·   sec x =       · sec x tan x = tan x
             dx   sec x dx         sec x


                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).

Check

             d
             dx
                =
                    1
                       ·
                         d
                  sec x dx
                           sec x =
                                     1
                                   sec x
                                         · sec x tan x = tan x            
                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
More Trig
Example
Find an antiderivative of f(x) = tan x.

Solution
???

Answer
F(x) = ln(sec x).

Check

             d
             dx
                =
                    1
                       ·
                         d
                  sec x dx
                           sec x =
                                     1
                                   sec x
                                         · sec x tan x = tan x            
More about this later.                                       .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   19 / 32
Outline


What is an antiderivative?

Tabulating Antiderivatives
   Power functions
   Combinations
   Exponential functions
   Trigonometric functions

Finding Antiderivatives Graphically

Rectilinear motion


                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   20 / 32
Problem
Below is the graph of a function f. Draw the graph of an antiderivative
for F.

                  y
                  .

                                      .

                                .                                                  . . = f(x)
                                                                                     y

                      .          .     .           .          .            .         .
                                                                                       x
                                                                                       .
                               1
                               .     2
                                     .           3
                                                 .          4
                                                            .            5
                                                                         .         6
                                                                                   .




                                                             .
                                                                               .     .     .     .       .     .

  V63.0121, Calculus I (NYU)               Section 4.7 Antiderivatives                         April 8, 2010   21 / 32
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:
                                                                           ′
                                 .    .    .    .    .    .       .. = F
                                                                   f

    y
    .                                1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .    .    .      .         .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:
                                                                           ′
                                 .    .. .
                                       +        .    .    .       .. = F
                                                                   f

    y
    .                                1
                                     .   2
                                         .     3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .    .    .      .         .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:
                                                                          ′
                                 .    .. .. .
                                       + +          .    .       .. = F
                                                                  f

    y
    .                                1
                                     .   2
                                         .  3
                                            .      4
                                                   .    5
                                                        .        6F
                                                                 ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .      .         .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                       + + −                              ′
                                 .    .. .. .. .         .       .. = F
                                                                  f

    y
    .                                1
                                     .   2
                                         .  3
                                            .  4
                                               .        5
                                                        .        6F
                                                                 ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .      .         .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                       + + − −                            ′
                                 .    .. .. .. .. .              .. = F
                                                                  f

    y
    .                                1
                                     .   2
                                         .  3
                                            .  4
                                               .  5
                                                  .              6F
                                                                 ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .      .         .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1
                                     .    2
                                          .   3
                                              .   4
                                                  .   5
                                                      .   6F
                                                          ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1↗2
                                     . . .    3
                                              .   4
                                                  .   5
                                                      .   6F
                                                          ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1↗2↗3
                                     . . . . .    4
                                                  .   5
                                                      .   6F
                                                          ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1↗2↗3↘4
                                     . . . . . . .    5
                                                      .   6F
                                                          ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1↗2↗3↘4↘5
                                     . . . . . . . . .    6F
                                                          ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . . . . . . . . . ..
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . . . . . . .
                                             max
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .
        .    . . . . . .
                          x
                          .
            1 2 3 4 5 6
            . . . . . .

                    .




                                               .    .   .    .   .   .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .                                          ′       ′′
        .    . . . . . .              .    .    .    .    .       .. = F
                                                                   f

            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..

                    .




                                               .    .    .    .        .        .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .                                          ′       ′′
        .    . . . . . .              .. + .
                                       +        .    .    .       .. = F
                                                                   f

            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..

                    .




                                               .    .    .    .        .        .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .                                          ′       ′′
        .    . . . . . .              .. + .. − .
                                       + −           .    .       .. = F
                                                                   f

            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..

                    .




                                                .   .    .    .        .        .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .                                          ′       ′′
        .    . . . . . .              .. + .. − .. − .
                                       + − −              .       .. = F
                                                                   f

            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..

                    .




                                                .   .    .    .        .        .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .                                          ′       ′′
        .    . . . . . .              .. + .. − .. − .. + .
                                       + − − +                    .. = F
                                                                   f

            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .        6F
                                                                  ..

                    .




                                               .    .    .    .        .        .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    6F
                                                              ..

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
                                        .
                                        ⌣
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    6F
                                                              ..

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
                                        ⌣ .
                                        .    ⌢
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    6F
                                                              ..

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
                                        ⌣ .
                                        .    ⌢ .  ⌢
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    6F
                                                              ..

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
                                        ⌣ .
                                        .    ⌢ .  ⌢ .  ⌣
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    6F
                                                              ..

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .              + − − + + f′                   ′′
        .    . . . . . .              .. + .. − .. − .. + .. + . . = F
                                        ⌣ .
                                        .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    .F
                                                              6

                    .




                                                .   .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2
                                            .   3
                                                .    4
                                                     .    5
                                                          .    .F
                                                               6
                                           IP
                    .




                                                .    .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .




                                                .    .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .     .    .    .        ..
                                                                     F
                                     1
                                     .    2
                                          .     3
                                                .    4
                                                     .    5
                                                          .        6s
                                                                   . . hape

                                                .    .    .    .       .      .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .     .    .    .        ..
                                                                     F
                                        .
                                     1
                                     .    2
                                          .     3
                                                .    4
                                                     .    5
                                                          .        6s
                                                                   . . hape

                                                .    .    .    .       .      .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .    .     .    .        ..
                                                                     F
                                        .    .
                                     1
                                     .    2
                                          .    3
                                               .     4
                                                     .    5
                                                          .        6s
                                                                   . . hape

                                                .    .    .    .       .      .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .    .    .     .        ..
                                                                     F
                                        .    .    .
                                     1
                                     .    2
                                          .    3
                                               .    4
                                                    .     5
                                                          .        6s
                                                                   . . hape

                                                .    .    .    .       .      .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .    .    .    .         ..
                                                                     F
                                        .    .    .    .
                                     1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .         6s
                                                                   . . hape

                                                .    .    .    .       .      .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                        + + − − + f              ′
                                 .    . . . . . . . . . . .. = F
    y
    .                                1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                     . . .. . . . .. . . . . .
                                             max      min
               .
             .          .               + − − + + f′                   ′′
        .    . . . . . .               .. + .. − .. − .. + .. + . . = F
                                         ⌣ .
                                         .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
            1 2 3 4 5 6
            . . . . . .
                          x
                          .          ..
                                      1     2 ..
                                            .   3     4
                                                      .   5
                                                          .    .F
                                                               6
                                           IP        IP
                    .
                                      .    .    .    .    .   ..F
                                        .    .    .    .    . . hape
                                     1
                                     .    2
                                          .    3
                                               .    4
                                                    .    5
                                                         .    .s
                                                              6

                                                .    .    .    .    .       .
Using f to make a sign chart for F

Assuming F′ = f, we can make a sign chart for f and f′ to find the
intervals of monotonicity and concavity for for F:

                                                 + + − − + f              ′
                                       .       . . . . . . . . . . .. = F
     y
     .                                        1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F
                                              . . .. . . . .. . . . . .
                                                      max      min
                  .
              .          .                      + − − + + f′                   ′′
         .    . . . . . .                      .. + .. − .. − .. + .. + . . = F
                                                 ⌣ .
                                                 .    ⌢ .  ⌢ .  ⌣ .  ⌣ .
             1 2 3 4 5 6
             . . . . . .
                           x
                           .                 ..
                                              1     2 ..
                                                    .   3     4
                                                              .   5
                                                                  .    .F
                                                                       6
                                                   IP        IP
                           .
                                      ?
                                      ..   ?
                                           ..   ?
                                                ..   ?
                                                     ..   ?
                                                          ..   ?F
                                                               .. .
                                         .    .    .    .    . . hape
                                      1
                                      .    2
                                           .    3
                                                .    4
                                                     .    5
                                                          .    .s
                                                               6
The only question left is: What are the function values?
                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   22 / 32
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .
Solution
                                                      .
                                                   .          ..
                                                               f
                                              .    . . . . . .
                                                               x
                                                               .
                                                  1 2 3 4 5 6
                                                  . . . . . .

                                                          .
                                                   . . . . .           ..
                                                                        F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .           6s
                                                                      . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .   .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .
Solution
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
                                                               x
                                                               .
                                                  1 2 3 4 5 6
                                                  . . . . . .

                                                          .
                                                   . . . . .           ..
                                                                        F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .           6s
                                                                      . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .   .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .
Solution
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .           ..
                                                                        F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .           6s
                                                                      . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .   .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .           ..
                                                                        F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .           6s
                                                                      . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .   .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .           ..
                                                                        F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .           6s
                                                                      . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .   .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .                   .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .               ..
                                                                            F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .               6s
                                                                          . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .       .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .                   .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .          ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .               ..
                                                                            F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .               6s
                                                                          . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .       .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .                   .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .     .    ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .               ..
                                                                            F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .               6s
                                                                          . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .       .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .                   .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .     .    ..
                                                               f
                                              .    . . . . . .
    Using the sign chart, we                                   x
                                                               .
    draw arcs with the                            1 2 3 4 5 6
                                                  . . . . . .
    specified monotonicity and
    concavity                                             .
                                                   . . . . .               ..
                                                                            F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .               6s
                                                                          . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .       .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                          y
                                          .                   .
Solution
                                                      .
                                                      .
    We start with F(1) = 0.                        .     .     ..
                                                                f
                                              .    . . . . . .
    Using the sign chart, we                                    x
                                                                .
    draw arcs with the                            . . . . .. .
                                                  1 2 3 4 5 6
    specified monotonicity and
    concavity                                             .
                                                   . . . . .               ..
                                                                            F
                                                    . . . . .
                                                  1 2 3 4 5
                                                  . . . . .               6s
                                                                          . . hape
                                                      IP
                                                      .
                                                      max
                                                      .
                                                      IP
                                                      .
                                                      min
                                                      .
                                                  .       .       .   .      .       .
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                                       y
                                                       .                     .
Solution
                                                                     .
                                                                     .
     We start with F(1) = 0.                                      .     .     ..
                                                                               f
                                                             .    . . . . . .
     Using the sign chart, we                                                  x
                                                                               .
     draw arcs with the                                          . . . . .. .
                                                                 1 2 3 4 5 6
     specified monotonicity and
     concavity                                                           .
                                                                  . . . . .                 ..
                                                                                             F
                                                                   . . . . .
                                                                 1 2 3 4 5
                                                                 . . . . .                 6s
                                                                                           . . hape
                                                                     IP
                                                                     .
                                                                     max
                                                                     .
                                                                     IP
                                                                     .
                                                                     min
                                                                     .
                                                                 .       .       .     .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                           April 8, 2010    23 / 32
Could you repeat the question?

Problem
Below is the graph of a function f. Draw the graph of the antiderivative
for F with F(1) = 0.

                                                       y
                                                       .                     .
Solution
                                                                     .
                                                                     .
     We start with F(1) = 0.                                      .     .     ..
                                                                               f
                                                             .    . . . . . .
     Using the sign chart, we                                                  x
                                                                               .
     draw arcs with the                                          . . . . .. .
                                                                 1 2 3 4 5 6
     specified monotonicity and
     concavity                                                           .
                                                                  . . . . .                 ..
                                                                                             F
     It’s harder to tell if/when F                                 . . . . .
     crosses the axis; more                                      1 2 3 4 5
                                                                 . . . . .                 6s
                                                                                           . . hape
                                                                     IP
                                                                     .
                                                                     max
                                                                     .
                                                                     IP
                                                                     .
                                                                     min
                                                                     .
     about that later.
                                                                 .       .       .     .       .      .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                           April 8, 2010    23 / 32
Outline


What is an antiderivative?

Tabulating Antiderivatives
   Power functions
   Combinations
   Exponential functions
   Trigonometric functions

Finding Antiderivatives Graphically

Rectilinear motion


                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   24 / 32
Say what?




    “Rectilinear motion” just means motion along a line.
    Often we are given information about the velocity or acceleration
    of a moving particle and we want to know the equations of motion.




                                                            .   .   .     .       .     .

 V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   25 / 32
Application: Dead Reckoning




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   26 / 32
Application: Dead Reckoning




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   26 / 32
Problem
Suppose a particle of mass m is acted upon by a constant force F.
Find the position function s(t), the velocity function v(t), and the
acceleration function a(t).




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   27 / 32
Problem
Suppose a particle of mass m is acted upon by a constant force F.
Find the position function s(t), the velocity function v(t), and the
acceleration function a(t).

Solution

     By Newton’s Second Law (F = ma) a constant force induces a
                                         F
     constant acceleration. So a(t) = a = .
                                         m




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   27 / 32
Problem
Suppose a particle of mass m is acted upon by a constant force F.
Find the position function s(t), the velocity function v(t), and the
acceleration function a(t).

Solution

     By Newton’s Second Law (F = ma) a constant force induces a
                                              F
     constant acceleration. So a(t) = a = .
                                              m
     Since v′ (t) = a(t), v(t) must be an antiderivative of the constant
     function a. So
                              v(t) = at + C = at + v0
     where v0 is the initial velocity.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   27 / 32
Problem
Suppose a particle of mass m is acted upon by a constant force F.
Find the position function s(t), the velocity function v(t), and the
acceleration function a(t).

Solution

     By Newton’s Second Law (F = ma) a constant force induces a
                                              F
     constant acceleration. So a(t) = a = .
                                              m
     Since v′ (t) = a(t), v(t) must be an antiderivative of the constant
     function a. So
                              v(t) = at + C = at + v0
     where v0 is the initial velocity.
     Since s′ (t) = v(t), s(t) must be an antiderivative of v(t), meaning

                                    1 2              1
                           s(t) =     at + v0 t + C = at2 + v0 t + s0
                                    2                2
                                                                     .   .   .     .       .     .

  V63.0121, Calculus I (NYU)           Section 4.7 Antiderivatives               April 8, 2010   27 / 32
An earlier Hatsumon

Example
Drop a ball off the roof of the Silver Center. What is its velocity when it
hits the ground?




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   28 / 32
An earlier Hatsumon

Example
Drop a ball off the roof of the Silver Center. What is its velocity when it
hits the ground?

Solution
Assume s0 = 100 m, and v0 = 0. Approximate a = g ≈ −10. Then

                        s(t) = 100 − 5t2
                    √      √
So s(t) = 0 when t = 20 = 2 5. Then

                               v(t) = −10t,
                                √           √
so the velocity at impact is v(2 5) = −20 5 m/s.

                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   28 / 32
Example
The skid marks made by an automobile indicate that its brakes were
fully applied for a distance of 160 ft before it came to a stop. Suppose
that the car in question has a constant deceleration of 20 ft/s2 under the
conditions of the skid. How fast was the car traveling when its brakes
were first applied?




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   29 / 32
Example
The skid marks made by an automobile indicate that its brakes were
fully applied for a distance of 160 ft before it came to a stop. Suppose
that the car in question has a constant deceleration of 20 ft/s2 under the
conditions of the skid. How fast was the car traveling when its brakes
were first applied?

Solution (Setup)

     While breaking, the car has acceleration a(t) = −20




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   29 / 32
Example
The skid marks made by an automobile indicate that its brakes were
fully applied for a distance of 160 ft before it came to a stop. Suppose
that the car in question has a constant deceleration of 20 ft/s2 under the
conditions of the skid. How fast was the car traveling when its brakes
were first applied?

Solution (Setup)

     While breaking, the car has acceleration a(t) = −20
     Measure time 0 and position 0 when the car starts braking. So
     s(0) = 0.
     The car stops at time some t1 , when v(t1 ) = 0.




                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   29 / 32
Example
The skid marks made by an automobile indicate that its brakes were
fully applied for a distance of 160 ft before it came to a stop. Suppose
that the car in question has a constant deceleration of 20 ft/s2 under the
conditions of the skid. How fast was the car traveling when its brakes
were first applied?

Solution (Setup)

     While breaking, the car has acceleration a(t) = −20
     Measure time 0 and position 0 when the car starts braking. So
     s(0) = 0.
     The car stops at time some t1 , when v(t1 ) = 0.
     We know that when s(t1 ) = 160.
     We want to know v(0), or v0 .

                                                             .   .   .     .       .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   29 / 32
Implementing the Solution

In general,
                                         1
                       s(t) = s0 + v0 t + at2
                                         2
Since s0 = 0 and a = −20, we have

                                s(t) = v0 t − 10t2
                                v(t) = v0 − 20t

for all t.




                                                              .   .   .     .       .     .

   V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives               April 8, 2010   30 / 32
Implementing the Solution

In general,
                                         1
                       s(t) = s0 + v0 t + at2
                                         2
Since s0 = 0 and a = −20, we have

                                  s(t) = v0 t − 10t2
                                  v(t) = v0 − 20t

for all t. Plugging in t = t1 ,

                                  160 = v0 t1 − 10t2
                                                   1
                                     0 = v0 − 20t1

We need to solve these two equations.

                                                                 .   .   .     .       .     .

  V63.0121, Calculus I (NYU)       Section 4.7 Antiderivatives               April 8, 2010   30 / 32
Solving
We have
                           v0 t1 − 10t2 = 160
                                      1                   v0 − 20t1 = 0




                                                                   .   .   .     .       .     .

  V63.0121, Calculus I (NYU)         Section 4.7 Antiderivatives               April 8, 2010   31 / 32
Solving
We have
                           v0 t1 − 10t2 = 160
                                      1                   v0 − 20t1 = 0


     The second gives t1 = v0 /20, so substitute into the first:

                                         v0     ( v )2
                                  v0 ·      − 10 0     = 160
                                         20       20
     or
                                v2     10v2
                                 0
                                    −     0
                                            = 160
                                20     400
                                   2v2 − v2 = 160 · 40 = 6400
                                     0    0




                                                                   .   .   .     .       .     .

  V63.0121, Calculus I (NYU)         Section 4.7 Antiderivatives               April 8, 2010   31 / 32
Solving
We have
                           v0 t1 − 10t2 = 160
                                      1                   v0 − 20t1 = 0


     The second gives t1 = v0 /20, so substitute into the first:

                                         v0     ( v )2
                                  v0 ·      − 10 0     = 160
                                         20       20
     or
                                v2     10v2
                                 0
                                    −     0
                                            = 160
                                20     400
                                   2v2 − v2 = 160 · 40 = 6400
                                     0    0



     So v0 = 80 ft/s ≈ 55 mi/hr
                                                                   .   .   .     .       .     .

  V63.0121, Calculus I (NYU)         Section 4.7 Antiderivatives               April 8, 2010   31 / 32
What have we learned today?




        Antiderivatives are a useful
        concept, especially in
        motion                                               y
                                                             .              .
        We can graph an                                                 .
                                                                        .
                                                                    .     .    ..
                                                                                f
        antiderivative from the                                  . . . . . . .
        graph of a function                                                     x
                                                                                .
                                                                   . . . . .. . F
                                                                   1 2 3 4 5 6
        We can compute
        antiderivatives, but not                                                .
        always
                                                                     f(x) = e−x
                                                                                    2


                                                                     f′ (x) = ???
                                                                 .      .       .       .     .     .

  V63.0121, Calculus I (NYU)   Section 4.7 Antiderivatives                          April 8, 2010   32 / 32

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Lesson 21: Antiderivatives (slides)

  • 1. Section 4.7 Antiderivatives V63.0121.006/016, Calculus I New York University April 8, 2010 Announcements Quiz April 16 on §§4.1–4.4 Final Exam: Monday, May 10, 10:00am . . Image credit: Ian Hampton . . . . . .
  • 2. Announcements Quiz April 16 on §§4.1–4.4 Final Exam: Monday, May 10, 10:00am . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 2 / 32
  • 3. Outline What is an antiderivative? Tabulating Antiderivatives Power functions Combinations Exponential functions Trigonometric functions Finding Antiderivatives Graphically Rectilinear motion . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 3 / 32
  • 4. Objectives Given an expression for function f, find a differentiable function F such that F′ = f (F is called an antiderivative for f). Given the graph of a function f, find a differentiable function F such that F′ = f Use antiderivatives to solve problems in rectilinear motion . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 4 / 32
  • 5. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 6. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 7. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? Example is F(x) = x ln x − x an antiderivative for f(x) = ln x? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 8. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? Example is F(x) = x ln x − x an antiderivative for f(x) = ln x? Solution d (x ln x − x) dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 9. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? Example is F(x) = x ln x − x an antiderivative for f(x) = ln x? Solution d 1 (x ln x − x) = 1 · ln x + x · − 1 dx x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 10. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? Example is F(x) = x ln x − x an antiderivative for f(x) = ln x? Solution d 1 (x ln x − x) = 1 · ln x + x · − 1 = ln x dx x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 11. Hard problem, easy check Example Find an antiderivative for f(x) = ln x. Solution ??? Example is F(x) = x ln x − x an antiderivative for f(x) = ln x? Solution d dx 1 (x ln x − x) = 1 · ln x + x · − 1 = ln x x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 5 / 32
  • 12. Why the MVT is the MITC Most Important Theorem In Calculus! Theorem Let f′ = 0 on an interval (a, b). Then f is constant on (a, b). Proof. Pick any points x and y in (a, b) with x y. Then f is continuous on [x, y] and differentiable on (x, y). By MVT there exists a point z in (x, y) such that f(y) − f(x) = f′ (z) =⇒ f(y) = f(x) + f′ (z)(y − x) y−x But f′ (z) = 0, so f(y) = f(x). Since this is true for all x and y in (a, b), then f is constant. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 6 / 32
  • 13. When two functions have the same derivative Theorem Suppose f and g are two differentiable functions on (a, b) with f′ = g′ . Then f and g differ by a constant. That is, there exists a constant C such that f(x) = g(x) + C. Proof. Let h(x) = f(x) − g(x) Then h′ (x) = f′ (x) − g′ (x) = 0 on (a, b) So h(x) = C, a constant This means f(x) − g(x) = C on (a, b) . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 7 / 32
  • 14. Outline What is an antiderivative? Tabulating Antiderivatives Power functions Combinations Exponential functions Trigonometric functions Finding Antiderivatives Graphically Rectilinear motion . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 8 / 32
  • 15. Antiderivatives of power functions y . .(x) = x2 f Recall that the derivative of a power function is a power function. Fact (The Power Rule) If f(x) = xr , then f′ (x) = rxr−1 . . x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 9 / 32
  • 16. Antiderivatives of power functions ′ y f . . (x) = 2x .(x) = x2 f Recall that the derivative of a power function is a power function. Fact (The Power Rule) If f(x) = xr , then f′ (x) = rxr−1 . . x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 9 / 32
  • 17. Antiderivatives of power functions ′ y f . . (x) = 2x .(x) = x2 f Recall that the derivative of a power function is a power function. F . (x) = ? Fact (The Power Rule) If f(x) = xr , then f′ (x) = rxr−1 . . x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 9 / 32
  • 18. Antiderivatives of power functions ′ y f . . (x) = 2x .(x) = x2 f Recall that the derivative of a power function is a power function. F . (x) = ? Fact (The Power Rule) If f(x) = xr , then f′ (x) = rxr−1 . So in looking for antiderivatives . of power functions, try power x . functions! . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 9 / 32
  • 19. Example Find an antiderivative for the function f(x) = x3 . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 20. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 21. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 22. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . r − 1 = 3 =⇒ r = 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 23. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 24. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 1 4 So F(x) = x is an antiderivative. 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 25. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 1 4 So F(x) = x is an antiderivative. 4 Check: ( ) d 1 4 1 x = 4 · x4−1 = x3 dx 4 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 26. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 1 4 So F(x) = x is an antiderivative. 4 Check: ( ) d 1 4 dx 4 1 x = 4 · x4−1 = x3 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 27. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 1 4 So F(x) = x is an antiderivative. 4 Check: ( ) d 1 4 dx 4 1 x = 4 · x4−1 = x3 4 Any others? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 28. Example Find an antiderivative for the function f(x) = x3 . Solution Try a power function F(x) = axr Then F′ (x) = arxr−1 , so we want arxr−1 = x3 . 1 r − 1 = 3 =⇒ r = 4, and ar = 1 =⇒ a = . 4 1 4 So F(x) = x is an antiderivative. 4 Check: ( ) d 1 4 dx 4 1 x = 4 · x4−1 = x3 4 1 4 Any others? Yes, F(x) = x + C is the most general form. 4 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 10 / 32
  • 29. Fact (The Power Rule for antiderivatives) If f(x) = xr , then 1 r+1 F(x) = x r+1 is an antiderivative for f… . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 11 / 32
  • 30. Fact (The Power Rule for antiderivatives) If f(x) = xr , then 1 r+1 F(x) = x r+1 is an antiderivative for f as long as r ̸= −1. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 11 / 32
  • 31. Fact (The Power Rule for antiderivatives) If f(x) = xr , then 1 r+1 F(x) = x r+1 is an antiderivative for f as long as r ̸= −1. Fact 1 If f(x) = x−1 = , then x F(x) = ln |x| + C is an antiderivative for f. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 11 / 32
  • 32. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 33. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d ln |x| dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 34. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d d ln |x| = ln(x) dx dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 35. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d d 1 ln |x| = ln(x) = dx dx x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 36. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 37. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d ln |x| dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 38. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d d ln |x| = ln(−x) dx dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 39. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d d 1 ln |x| = ln(−x) = · (−1) dx dx −x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 40. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d d 1 1 ln |x| = ln(−x) = · (−1) = dx dx −x x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 41. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d dx ln |x| = d dx ln(−x) = 1 −x · (−1) = 1 x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 42. What's with the absolute value? { ln(x) if x 0; F(x) = ln |x| = ln(−x) if x 0. The domain of F is all nonzero numbers, while ln x is only defined on positive numbers. If x 0, d dx ln |x| = d dx ln(x) = 1 x If x 0, d dx ln |x| = d dx ln(−x) = 1 −x · (−1) = 1 x We prefer the antiderivative with the larger domain. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 12 / 32
  • 43. Graph of ln |x| y . . f .(x) = 1/x x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 13 / 32
  • 44. Graph of ln |x| y . F . (x) = ln(x) . f .(x) = 1/x x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 13 / 32
  • 45. Graph of ln |x| y . . (x) = ln |x| F . f .(x) = 1/x x . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 13 / 32
  • 46. Combinations of antiderivatives Fact (Sum and Constant Multiple Rule for Antiderivatives) If F is an antiderivative of f and G is an antiderivative of g, then F + G is an antiderivative of f + g. If F is an antiderivative of f and c is a constant, then cF is an antiderivative of cf. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 14 / 32
  • 47. Combinations of antiderivatives Fact (Sum and Constant Multiple Rule for Antiderivatives) If F is an antiderivative of f and G is an antiderivative of g, then F + G is an antiderivative of f + g. If F is an antiderivative of f and c is a constant, then cF is an antiderivative of cf. Proof. These follow from the sum and constant multiple rule for derivatives: If F′ = f and G′ = g, then (F + G)′ = F′ + G′ = f + g Or, if F′ = f, (cF)′ = cF′ = cf . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 14 / 32
  • 48. Antiderivatives of Polynomials Example Find an antiderivative for f(x) = 16x + 5. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 15 / 32
  • 49. Antiderivatives of Polynomials Example Find an antiderivative for f(x) = 16x + 5. Solution 1 2 The expression x is an antiderivative for x, and x is an antiderivative 2 for 1. So ( ) 1 2 F(x) = 16 · x + 5 · x + C = 8x2 + 5x + C 2 is the antiderivative of f. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 15 / 32
  • 50. Antiderivatives of Polynomials Example Find an antiderivative for f(x) = 16x + 5. Solution 1 2 The expression x is an antiderivative for x, and x is an antiderivative 2 for 1. So ( ) 1 2 F(x) = 16 · x + 5 · x + C = 8x2 + 5x + C 2 is the antiderivative of f. Question Why do we not need two C’s? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 15 / 32
  • 51. Antiderivatives of Polynomials Example Find an antiderivative for f(x) = 16x + 5. Solution ( ) 1 2 F(x) = 16 · x + 5 · x + C = 8x2 + 5x + C 2 Question Why do we not need two C’s? Answer A combination of two arbitrary constants is still an arbitrary constant. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 15 / 32
  • 52. Exponential Functions Fact If f(x) = ax , f′ (x) = (ln a)ax . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 16 / 32
  • 53. Exponential Functions Fact If f(x) = ax , f′ (x) = (ln a)ax . Accordingly, Fact 1 x If f(x) = ax , then F(x) = a + C is the antiderivative of f. ln a . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 16 / 32
  • 54. Exponential Functions Fact If f(x) = ax , f′ (x) = (ln a)ax . Accordingly, Fact 1 x If f(x) = ax , then F(x) = a + C is the antiderivative of f. ln a Proof. Check it yourself. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 16 / 32
  • 55. Exponential Functions Fact If f(x) = ax , f′ (x) = (ln a)ax . Accordingly, Fact 1 x If f(x) = ax , then F(x) = a + C is the antiderivative of f. ln a Proof. Check it yourself. In particular, Fact If f(x) = ex , then F(x) = ex + C is the antiderivative of f. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 16 / 32
  • 56. Logarithmic functions? Remember we found F(x) = x ln x − x is an antiderivative of f(x) = ln x. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 17 / 32
  • 57. Logarithmic functions? Remember we found F(x) = x ln x − x is an antiderivative of f(x) = ln x. This is not obvious. See Calc II for the full story. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 17 / 32
  • 58. Logarithmic functions? Remember we found F(x) = x ln x − x is an antiderivative of f(x) = ln x. This is not obvious. See Calc II for the full story. ln x However, using the fact that loga x = , we get: ln a Fact If f(x) = loga (x) 1 1 F(x) = (x ln x − x) + C = x loga x − x+C ln a ln a is the antiderivative of f(x). . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 17 / 32
  • 59. Trigonometric functions Fact d d sin x = cos x cos x = − sin x dx dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 18 / 32
  • 60. Trigonometric functions Fact d d sin x = cos x cos x = − sin x dx dx So to turn these around, Fact The function F(x) = − cos x + C is the antiderivative of f(x) = sin x. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 18 / 32
  • 61. Trigonometric functions Fact d d sin x = cos x cos x = − sin x dx dx So to turn these around, Fact The function F(x) = − cos x + C is the antiderivative of f(x) = sin x. The function F(x) = sin x + C is the antiderivative of f(x) = cos x. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 18 / 32
  • 62. More Trig Example Find an antiderivative of f(x) = tan x. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 63. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 64. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 65. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). Check d 1 d = · sec x dx sec x dx . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 66. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). Check d 1 d 1 = · sec x = · sec x tan x dx sec x dx sec x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 67. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). Check d 1 d 1 = · sec x = · sec x tan x = tan x dx sec x dx sec x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 68. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). Check d dx = 1 · d sec x dx sec x = 1 sec x · sec x tan x = tan x . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 69. More Trig Example Find an antiderivative of f(x) = tan x. Solution ??? Answer F(x) = ln(sec x). Check d dx = 1 · d sec x dx sec x = 1 sec x · sec x tan x = tan x More about this later. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 19 / 32
  • 70. Outline What is an antiderivative? Tabulating Antiderivatives Power functions Combinations Exponential functions Trigonometric functions Finding Antiderivatives Graphically Rectilinear motion . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 20 / 32
  • 71. Problem Below is the graph of a function f. Draw the graph of an antiderivative for F. y . . . . . = f(x) y . . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6 . . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 21 / 32
  • 72. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: ′ . . . . . . .. = F f y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 73. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: ′ . .. . + . . . .. = F f y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 74. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: ′ . .. .. . + + . . .. = F f y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 75. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − ′ . .. .. .. . . .. = F f y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 76. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − ′ . .. .. .. .. . .. = F f y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 77. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 78. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1↗2 . . . 3 . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 79. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1↗2↗3 . . . . . 4 . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 80. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1↗2↗3↘4 . . . . . . . 5 . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 81. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1↗2↗3↘4↘5 . . . . . . . . . 6F .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 82. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . . . . . . . . . .. . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 83. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . . . . . . . max . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 84. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .
  • 85. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . ′ ′′ . . . . . . . . . . . . .. = F f 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 86. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . ′ ′′ . . . . . . . .. + . + . . . .. = F f 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 87. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . ′ ′′ . . . . . . . .. + .. − . + − . . .. = F f 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 88. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . ′ ′′ . . . . . . . .. + .. − .. − . + − − . .. = F f 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 89. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . ′ ′′ . . . . . . . .. + .. − .. − .. + . + − − + .. = F f 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 90. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 91. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F . ⌣ 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 92. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 93. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 94. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . 6F .. . . . . . . .
  • 95. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . 1 . 2 . 3 . 4 . 5 . .F 6 . . . . . . .
  • 96. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 . 3 . 4 . 5 . .F 6 IP . . . . . . .
  • 97. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .
  • 98. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .. F 1 . 2 . 3 . 4 . 5 . 6s . . hape . . . . . .
  • 99. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .. F . 1 . 2 . 3 . 4 . 5 . 6s . . hape . . . . . .
  • 100. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .. F . . 1 . 2 . 3 . 4 . 5 . 6s . . hape . . . . . .
  • 101. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .. F . . . 1 . 2 . 3 . 4 . 5 . 6s . . hape . . . . . .
  • 102. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . .. F . . . . 1 . 2 . 3 . 4 . 5 . 6s . . hape . . . . . .
  • 103. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . . . . . . ..F . . . . . . hape 1 . 2 . 3 . 4 . 5 . .s 6 . . . . . .
  • 104. Using f to make a sign chart for F Assuming F′ = f, we can make a sign chart for f and f′ to find the intervals of monotonicity and concavity for for F: + + − − + f ′ . . . . . . . . . . . .. = F y . 1 ↗ 2 ↗ 3 ↘ 4 ↘ 5 ↗ 6F . . .. . . . .. . . . . . max min . . . + − − + + f′ ′′ . . . . . . . .. + .. − .. − .. + .. + . . = F ⌣ . . ⌢ . ⌢ . ⌣ . ⌣ . 1 2 3 4 5 6 . . . . . . x . .. 1 2 .. . 3 4 . 5 . .F 6 IP IP . ? .. ? .. ? .. ? .. ? .. ?F .. . . . . . . . hape 1 . 2 . 3 . 4 . 5 . .s 6 The only question left is: What are the function values? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 22 / 32
  • 105. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . Solution . . .. f . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 106. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . Solution . We start with F(1) = 0. . .. f . . . . . . . x . 1 2 3 4 5 6 . . . . . . . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 107. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . Solution . We start with F(1) = 0. . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 108. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . Solution . . We start with F(1) = 0. . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 109. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . Solution . . We start with F(1) = 0. . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 110. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 111. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 112. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 113. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . . .. f . . . . . . . Using the sign chart, we x . draw arcs with the 1 2 3 4 5 6 . . . . . . specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 114. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . . .. f . . . . . . . Using the sign chart, we x . draw arcs with the . . . . .. . 1 2 3 4 5 6 specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . .
  • 115. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . . .. f . . . . . . . Using the sign chart, we x . draw arcs with the . . . . .. . 1 2 3 4 5 6 specified monotonicity and concavity . . . . . . .. F . . . . . 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 23 / 32
  • 116. Could you repeat the question? Problem Below is the graph of a function f. Draw the graph of the antiderivative for F with F(1) = 0. y . . Solution . . We start with F(1) = 0. . . .. f . . . . . . . Using the sign chart, we x . draw arcs with the . . . . .. . 1 2 3 4 5 6 specified monotonicity and concavity . . . . . . .. F It’s harder to tell if/when F . . . . . crosses the axis; more 1 2 3 4 5 . . . . . 6s . . hape IP . max . IP . min . about that later. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 23 / 32
  • 117. Outline What is an antiderivative? Tabulating Antiderivatives Power functions Combinations Exponential functions Trigonometric functions Finding Antiderivatives Graphically Rectilinear motion . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 24 / 32
  • 118. Say what? “Rectilinear motion” just means motion along a line. Often we are given information about the velocity or acceleration of a moving particle and we want to know the equations of motion. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 25 / 32
  • 119. Application: Dead Reckoning . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 26 / 32
  • 120. Application: Dead Reckoning . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 26 / 32
  • 121. Problem Suppose a particle of mass m is acted upon by a constant force F. Find the position function s(t), the velocity function v(t), and the acceleration function a(t). . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 27 / 32
  • 122. Problem Suppose a particle of mass m is acted upon by a constant force F. Find the position function s(t), the velocity function v(t), and the acceleration function a(t). Solution By Newton’s Second Law (F = ma) a constant force induces a F constant acceleration. So a(t) = a = . m . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 27 / 32
  • 123. Problem Suppose a particle of mass m is acted upon by a constant force F. Find the position function s(t), the velocity function v(t), and the acceleration function a(t). Solution By Newton’s Second Law (F = ma) a constant force induces a F constant acceleration. So a(t) = a = . m Since v′ (t) = a(t), v(t) must be an antiderivative of the constant function a. So v(t) = at + C = at + v0 where v0 is the initial velocity. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 27 / 32
  • 124. Problem Suppose a particle of mass m is acted upon by a constant force F. Find the position function s(t), the velocity function v(t), and the acceleration function a(t). Solution By Newton’s Second Law (F = ma) a constant force induces a F constant acceleration. So a(t) = a = . m Since v′ (t) = a(t), v(t) must be an antiderivative of the constant function a. So v(t) = at + C = at + v0 where v0 is the initial velocity. Since s′ (t) = v(t), s(t) must be an antiderivative of v(t), meaning 1 2 1 s(t) = at + v0 t + C = at2 + v0 t + s0 2 2 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 27 / 32
  • 125. An earlier Hatsumon Example Drop a ball off the roof of the Silver Center. What is its velocity when it hits the ground? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 28 / 32
  • 126. An earlier Hatsumon Example Drop a ball off the roof of the Silver Center. What is its velocity when it hits the ground? Solution Assume s0 = 100 m, and v0 = 0. Approximate a = g ≈ −10. Then s(t) = 100 − 5t2 √ √ So s(t) = 0 when t = 20 = 2 5. Then v(t) = −10t, √ √ so the velocity at impact is v(2 5) = −20 5 m/s. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 28 / 32
  • 127. Example The skid marks made by an automobile indicate that its brakes were fully applied for a distance of 160 ft before it came to a stop. Suppose that the car in question has a constant deceleration of 20 ft/s2 under the conditions of the skid. How fast was the car traveling when its brakes were first applied? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 29 / 32
  • 128. Example The skid marks made by an automobile indicate that its brakes were fully applied for a distance of 160 ft before it came to a stop. Suppose that the car in question has a constant deceleration of 20 ft/s2 under the conditions of the skid. How fast was the car traveling when its brakes were first applied? Solution (Setup) While breaking, the car has acceleration a(t) = −20 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 29 / 32
  • 129. Example The skid marks made by an automobile indicate that its brakes were fully applied for a distance of 160 ft before it came to a stop. Suppose that the car in question has a constant deceleration of 20 ft/s2 under the conditions of the skid. How fast was the car traveling when its brakes were first applied? Solution (Setup) While breaking, the car has acceleration a(t) = −20 Measure time 0 and position 0 when the car starts braking. So s(0) = 0. The car stops at time some t1 , when v(t1 ) = 0. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 29 / 32
  • 130. Example The skid marks made by an automobile indicate that its brakes were fully applied for a distance of 160 ft before it came to a stop. Suppose that the car in question has a constant deceleration of 20 ft/s2 under the conditions of the skid. How fast was the car traveling when its brakes were first applied? Solution (Setup) While breaking, the car has acceleration a(t) = −20 Measure time 0 and position 0 when the car starts braking. So s(0) = 0. The car stops at time some t1 , when v(t1 ) = 0. We know that when s(t1 ) = 160. We want to know v(0), or v0 . . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 29 / 32
  • 131. Implementing the Solution In general, 1 s(t) = s0 + v0 t + at2 2 Since s0 = 0 and a = −20, we have s(t) = v0 t − 10t2 v(t) = v0 − 20t for all t. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 30 / 32
  • 132. Implementing the Solution In general, 1 s(t) = s0 + v0 t + at2 2 Since s0 = 0 and a = −20, we have s(t) = v0 t − 10t2 v(t) = v0 − 20t for all t. Plugging in t = t1 , 160 = v0 t1 − 10t2 1 0 = v0 − 20t1 We need to solve these two equations. . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 30 / 32
  • 133. Solving We have v0 t1 − 10t2 = 160 1 v0 − 20t1 = 0 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 31 / 32
  • 134. Solving We have v0 t1 − 10t2 = 160 1 v0 − 20t1 = 0 The second gives t1 = v0 /20, so substitute into the first: v0 ( v )2 v0 · − 10 0 = 160 20 20 or v2 10v2 0 − 0 = 160 20 400 2v2 − v2 = 160 · 40 = 6400 0 0 . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 31 / 32
  • 135. Solving We have v0 t1 − 10t2 = 160 1 v0 − 20t1 = 0 The second gives t1 = v0 /20, so substitute into the first: v0 ( v )2 v0 · − 10 0 = 160 20 20 or v2 10v2 0 − 0 = 160 20 400 2v2 − v2 = 160 · 40 = 6400 0 0 So v0 = 80 ft/s ≈ 55 mi/hr . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 31 / 32
  • 136. What have we learned today? Antiderivatives are a useful concept, especially in motion y . . We can graph an . . . . .. f antiderivative from the . . . . . . . graph of a function x . . . . . .. . F 1 2 3 4 5 6 We can compute antiderivatives, but not . always f(x) = e−x 2 f′ (x) = ??? . . . . . . V63.0121, Calculus I (NYU) Section 4.7 Antiderivatives April 8, 2010 32 / 32