Page 665 - Algebra 1

Example
4
Writing a Linear Inequality Given the Graph
Write an inequality for the region graphed on each coordinate plane.
a.
SOLUTION
Determine the equation of the boundary line. It is a horizontal line that cuts through the y-axis at -1.
The equation of the boundary line is y = -1.
Then decide which inequality symbol to use for this graph.
The graph is shaded below the solid boundary line, so the inequality contains the ≤ symbol.
The inequality shown on the graph is y ≤ -1. b.
SOLUTION
Determine the equation of the boundary line. It has a y-intercept at -4 and a slope of 1.
The equation of the boundary line is y = x - 4.
Then decide which inequality symbol to use for this graph.
The graph is shaded above the dashed boundary line, so the inequality contains the > symbol.
The inequality shown on the graph is y > x - 4. Application: Carnival
Kia will attend a school carnival and she plans to spend no more than $12. Each game costs $2 and each item of food costs $3. Write and graph an inequality to describe the total cost of the carnival.
y
4
2
O
x
-4
-2
2
4
-2
-4
y
8
4
x
O
-8
-4
4
8
-8
Example
5
650 Saxon Algebra 1