Lesson 11-8

Graphing Linear Inequalitiespp. 548-551

EQ: How do you solve systems of linear equations by graphing?

Vocabulary to look for in this lesson:

• Boundary• Half plane

EQ: How do you solve systems of linear equations by graphing?

• To graph an inequality such as y<x+1, first graph the related equation y = x + 1.

• This is the boundary.– If the inequality contains the symbol ≤ or ≥, a solid line is

used to show that the boundary is included in the graph. – If the inequality contains the symbol < or >, a dashed line

is used to indicate that the boundary is not included in the graph

• Next, test any point above or below the line to decide which region is the solution for y<x+1.– For example, it is easy to test (0,0)

• Since 0<1 is true, (0,0) is a solution of y<x+1.

• Shade the region that contains this solution.

• This region is called a half plane.• All points in this region are solutions of

the inequality.

Example – Graph an Inequality

• The solution of an inequality includes negative numbers and fractions too.• In real life situations, though,

sometimes negative numbers and fractions have no meaning.

Example – Graph an Inequality to Solve a Problem

• Class work: p. 550 # 3-7 all• Homework: pp. 550 # 8-22 evens

EQ: How do you solve systems of linear equations by graphing?