Writing linear equations

Warm Up
Mardi 5 octobre
Order the following numbers from least to
greatest.
√36, -√2, (-0.4)2
, -3, 15%, √3

Mercredi 6 Octobre
Warm up
A linear function has a y-intercept of 3 and a slope
of 5. What's the right function rule?
A. y = 5x + 3 C. y = 3x + 5
B. y = 8x D. y = 5*3x

Using linear function to predict the future...
Example 1: Baby's height and age
A baby is 20 inches long at birth. Assuming her
growth is linear with a slope (or rate) of .25 inches
per month, how tall will the baby be when he'll turn
2 ?

Could we solve this problem with 8th grade tools...
f(x) = ...... x + .......
f(24) =

·Being able to write a linear function rule
knowing the slope and the coordinates of one
point can be very helpful to predict the future.
·This will be the 1st objective we will work on this
week

Writing equations in slope intercept form
Obj. 1 : Knowing the slope and 1 point
Ex: Write the linear equation of a line with a slope of 3 and
going through (2, 8)

Step 1: Write the general form of a linear equation
y = mx + b
Step 2: Write the value of the slope for m in the
equation
here y = 3x + b
Step 3: Plug in the coordinates of the point for x
and y in order to find b
8 = 3*2 +
b
8 = 6 + b
Step 4: Write the equation in slope intercept form

Guided practice
Ex 1: Find the linear equation of a line going
through (1, 4) with a slope of 2

Ex 2: Find the linear equation of a line going
through (-2, 5) with a slope of 4

Extra help :
1)Write the linear equation of the line with a slope
of 2 and passing through (3, 10)
2) Write the linear equation of the line with a slope
of -3 and passing through (1, 4)

Jeudi 7 Octobre
Warm up
Which line has a slope of 3 and passes through the
point (1, 8)
A. y = 5x + 3 C. y = 3x + 5
B. y = 3x + 8 D. y = 1x + 8

Example 2: movie ticket price
A movie ticket price cost $5.50 in 2000. It costs in
2010, $8 on average. Assuming the increase in
price is linear and will continue to be, how much
will a movie ticket cost in 2023?

·In situations like these, it could be very helpful to
be able to write the function rule knowing the
coordinates of the 2 points.
·This way, we can use the function rule to predict
the future..
·Writing a function rule knowing the coordinates
of 2 points will be our 2nd goal this week!

Writing equations in slope intercept form
Obj. 2 : Knowing 2 points the line passes through
Ex: Write the linear equation of a line passing through
(1,2) and (3,8)

Step 1: Write y=mx +b
Step 2: Find the slope using slope
formula
Step 3: Plug in slope into function rule
Step 4: Use one of the 2 points to find b
Step 5: Write function rule

Guided practice
Ex 1: What is the linear equation of the line
passing through (2, 4) and (3, 8) ?
S1:
S2:
S3:
S4:
S5:

Ex 2: What is the linear equation of the line
passing through (-1, 4) and (2, 10) ?
S1:
S2:
S3:
S4:
S5:

Extra help : guided practice
Find the slope of the line going through
1. (1,3) and (2,8)

Vendredi 8 Octobre
Warm up
Write the linear equation of the line going through
(3,8) and (-1, 0)
S1 S5:
S2
S3
S4

Independent practice 1
For each of the following 4 problems, find the linear equation of
the line going through the 2 given points
1. (2,6) and (4, 10) 2. (3, 7) and (1,
13)
3. (1,-3) and (-4, 2) 4. (-1,-4) and (2, 11)

Obj. 1: slope and 1 point Obj. 2: 2 points

Review activity
1. Write the linear equation of the line going
through (2,8) with a slope of 3
S1:
S2:
S3:
S4:

2. Write the linear equation of the line going throug
(1, 5) with a slope of -2
S1:
S2:
S3:
S4:

3. Write the linear equation of the line going through
(1, 5) and (3, 9)
S1:
S2:
S3:
S4:

(-2,6) and (0,-2)
S1:
S2:
S3:
S4:

5. Write the linear equation of the line going throug
(-4,-10) with a slope of 5
S1:
S2:
S3:
S4:

(-1 , -3) and (1 , 7)
S1:
S2:
S3:
S4:

Quiz #4
1. Write the linear equation of
the line passing through (1,4)
with a slope of 3
S1:
S2:
S3:
S4:
2. Write the linear equation of
the line passing through
(3,8) and (7, 20)
S1:
S2:
S3:
S4:
g

Writing linear equations

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Writing linear equations