Page 660 - Algebra 1

9L A B
Graphing Linear Inequalities
Graphing Calculator Lab (Use with Lesson 97)
Linear inequalities in two variables can be graphed by hand or with a graphing calculator. Begin by following the process used to graph a linear equation. Then change the settings to shade the region of the coordinate system that makes the inequality true.
Graph the solution set of the inequality y > 2x - 7.
1. Enter the equation y = 2x - 7 into the
Y = editor.
2. Graph the equation by pressing and
selecting 6:ZStandard.
The line represents the boundary of the
solution set of the inequality y > 2x - 7. The solution set of the inequality is either the region above or the region below the line y = 2x - 7.
Use a test point to determine which region makes the inequality true.
Choose a test point that is not on the graph of the line y = 2x - 7.
The point (0, 0) is a good test point because it does not fall on the boundary line.
Substitute 0 for both x and y in the inequality. This substitution gives
0 > 2 · 0 - 7, or 0 > -7, which is true.
Since the point (0, 0) satisfies the inequality, the solution set is the region that contains the point (0, 0).
3. Shade the region above the line y = 2x - 7.
To graph this region, press . Then press
the key twice. The cursor moves to the
left of Y1 over an icon that looks like a line segment, \.
Press twice to choose the icon, which resembles a shaded region above a line.
Graphing Calculator Tip
For help with entering an equation into the Y= editor, see the graphing calculator keystrokes in Lab 3 on page 305.
Online Connection www.SaxonMathResources.com
Lab 9 645