Algebra 6.6Solving Systems of Linear

Inequalities

Learning TargetsLanguage Goal• Students will be able to graph systems of linear

inequalities in two variables.

Math Goal• Students will be able to graph and solve

systems of linear inequalities in two variables.

Essential Questions• How do we know where to shade in our graph

of a system of linear inequalities?

Warm-up

Homework Check

Homework Check

Vocabulary

•System of Linear Inequalities:

a set of two or more linear inequalities containing two or more variables.

•Solution of a System of Linear Inequalities:

all of the ordered pairs that satisfy all the linear inequalities in the system.

Example 1: Identifying Solutions of Systems of Linear Inequalities

Tell whether the ordered pair is a solution of the inequality.A. B.

Example 1: Identifying Solutions of Systems of Linear Inequalities

Tell whether the ordered pair is a solution of the inequality.C. D.

Graphing Systems of Linear Inequalities

Example 2:

+ =

1. Graph the first inequality. Remember dotted and solid lines and shading.

2. Graph the second inequality on the same coordinate plane including shading.

3. Then find where the two shadings overlap. This is your solutions!

Example 2: Solving a system of Linear Inequalities by GraphingGraph the system of linear inequalities. Give two ordered pairs that are solutions.

A.

Order pair solutions ______ ______

Example 2: Solving a system of Linear Inequalities by GraphingGraph the system of linear inequalities. Give two ordered pairs that are solutions.

B.

Order pair solutions ______ ______

Example 2: Solving a system of Linear Inequalities by GraphingGraph the system of linear inequalities. Give two ordered pairs that are solutions.

C.

Order pair solutions ______ ______

Example 3: Graphing Systems with Parallel BoundariesGraph the system of linear inequalities..

A.

Example 3: Graphing Systems with Parallel BoundariesGraph the system of linear inequalities..

B.

Example 3: Graphing Systems with Parallel BoundariesGraph the system of linear inequalities..

C.

Example 4: Word ProblemsA. A surf show makes the profits given in the table. The shop owner sells at least 10 surfboards and at least 20 wakeboards per month. He wants to earn at least $2000 a month. Show and describe all possible combinations of surfboards and wakeboards that the store owner needs to sell to meet his goals. List two possible combinations.1. Write a system of inequalities. Let x represent the number of surfboards and y represent the number of wakeboards.2. Graph the system. The graph should be in the first quadrant because sales are not negative.3. Describe all possible combinations. 4. List two possible combinations.

Surfboard 150

Wakeboard

100

Order pair solutions ______ ______

Example 4: Word ProblemsB. At her party, Alice is serving pepper jack cheese and cheddar cheese. She wants to have at least 2 pounds of each. Alice wants to spend at most $20 on cheese. Show and describe all possible combinations of the two cheeses Alice could buy. List two possible combinations.

Pepper Jack 4 Cheddar 2

Order pair solutions ______ ______

Graphing With Style WS

x

y

x

y

1. Graph the system of linear inequalities. 2. Graph the system of linear inequalities.

2

3

y

x

2 1

12

y x

y x

Graphing With Style WS

x

y

x

y

3. Graph the system of linear inequalities. 4. Graph the system of linear inequalities.

2 3 6

2 3 9

x y

x y

xy

xy

2

32

Lesson Quiz