PPT 6.8 Graphing Linear Inequalities.ppt

How to Determine
the Type of Line to Draw
Inequality
Symbol
Type of Line
> or < Dotted Line
> or < Solid Line

Choose the type of line
for the inequality given.
1. y > 3x - 2
a. Solid b. Dotted
2. y > ¼x - 5
a. Solid b. Dotted

Choose the inequality symbol for the
line shown.
< or >

If the
inequality is:
Shade
y > mx + b
or
y > mx + b
Above the
line
y < mx + b
or
y < mx + b
Below the line

x
y
Graph y > x - 2.
1. Graph
the line
y = x - 2.
2. Since y >, shade
above the line.

x
y
Graph y < x - 2.
1. Graph
the line
y = x - 2.
2. Since y <, shade
below the line.

Do you do
anything
different when
the line is dotted
rather than
solid?
Lesson
Start

x
y
Graph y > x - 2.
2. Since y >, shade
above the line.
1. Graph
the line
y = x - 2,
but make
the line
dotted.

x
y
Graph y < x - 2.
1. Graph
the line
y = x - 2,
but make
the line
dotted.
2. Since y <, shade
below the line.

y
Graph y > -½x + 3
Type of
line:
Solid
Dotted

x
y
Graph y > -½x + 3
Type of
line:
Solid
Dotted
Shade ___ the line.
Above Below
Lesson
Start

x
y
Graph y > -½x + 3
Type of
line:
Solid
Dotted
Shade ___ the line.
Above Below

x
y
Choose the correct inequality for the graph shown.
y < 1/3 x + 2
y < 1/3 x + 2
y > 1/3 x + 2
y > 1/3 x + 2

Where to Shade for Undefined or
No Slopes:
The inequality must be in
x  # (no y)
format.
 can be:
>, >, <, or <.

If the
inequality is:
Shade
To the
x > #
or
x > #
Right of the
line
x < #
or
x < #
Left of the line

x
y
Graph x > -2
1. Draw
a dotted
vertical
line at x
= -2.
2. Shade to
the right of
the line.

x
y
Graph x < -2.
1. Graph
the line
X = -2.
2. Shade
to the left
of the line.

x
y
Graph x > 3.
Choose type of
line.
Solid
Dotted

x
y
Graph x > 3.
Choose type of
line.
Solid
Choose
where to
shade.
Left Right

x
y
Graph x > 3.
Choose type of
line.
Solid
Choose
where to
shade.
Right

Solve -3x - 2y < 12.
+3x +3x
-2y < 3x + 12
-2 -2 -2
y < -3/2 x - 6
>

Choose the correct inequality.
1. 2x + 5y > -10
y > -2/5 x - 2
y < -2/5 x - 2
y > 2/5 x + 2 y < 2/5 x + 2
2. 3x - 2y > 10
y > -2/3 x - 5 y < -2/3 x - 5
y > 2/3 x - 5
y < 2/3 x - 5

Example 1
 Which ordered pair is a solution of
5x - 2y ≤ 6?
A. (0, -3)
B. (5, 5)
C. (1, -2)
D. (3, 3)

Example 2
 Graph the inequality x ≤ 4 in a coordinate
plane.
 Decide whether to
use a solid or
dashed line.
 Use (0, 0) as a
test point.
 Shade where the
solutions will be.
y
x
5
5
-5
-5

Example 3
 Graph 3x - 4y > 12 in a coordinate plane.
 Sketch the boundary line of the graph.
 Solve for “y” first:
 y < ¾x - 3
 Solid or dashed
line?
 Use (0, 0) as a
test point.
 Shade where the
solutions are.
y
x
5
5
-5
-5

Example 4:
 Graph y < 2/5x in a coordinate plane.
• What is the slope and y-intercept?
• m = 2/5
• b = (0,0)
• Solid or dashed
line?
 Use a test point
OTHER than the
origin.
 Shade where the
solutions are.
y
x
5
5
-5
-5

Graph: y ≥ -3/2x + 1
Step 1: graph
the boundary
(the line is
solid ≥)
Step 2: test
a point NOT
On the line
(0,0) is always
The easiest if it’s
Not on the line!!
3(0) + 2(0) ≥ 2
0 ≥ 2
Not a solution So shade the other side of the line!!

PPT 6.8 Graphing Linear Inequalities.ppt

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PPT 6.8 Graphing Linear Inequalities.ppt