## Presentation on theme: "8.3 Linear Inequalities in Two Variables BobsMathClass.Com Copyright © 2010 All Rights Reserved. 1 4.The next step is to determine which side of the line."— Presentation transcript:

8.3 Linear Inequalities in Two Variables BobsMathClass.Com Copyright © 2010 All Rights Reserved. 2 Step 1. Write the inequality as an equation. Step 2. Find 3 points. Step 3. Since the inequality symbol is , draw a solid line. Step 4. Pick a test point not on the line to determine which point to shade. Next Slide x y Let x=0, solve for y. Then let y=0, solve for x. 0 0 2 3 Now we need a third point. Choose any value for x except 0 and 2. Let’s choose x=4. 4 -3 Test Point: Since this is true, shade the side of the test point.

8.3 Linear Inequalities in Two Variables BobsMathClass.Com Copyright © 2010 All Rights Reserved. 4 Graphing Inequalities involving Vertical and Horizontal Lines Recall: The graph of an equation y=k, where k is any real number, is a horizontal line. The graph of an equation x=c, where c is any real number, is a vertical line. 1. Graph the line y=2. y=# is a horizontal line. Since the inequality is <, draw a dashed line. 2. Choose a test point. Next Slide Then use a test point to determine which side to shade. (0,0) (0,0) is usually chosen because the math will be easier. The only time we can not choose (0,0) is if the line goes through (0,0), the origin. Therefore, shade the side that does not have the test point.

8.3 Linear Inequalities in Two Variables BobsMathClass.Com Copyright © 2010 All Rights Reserved. 6 2. Graph the line x=-2. x=# is a vertical line. Since the inequality is >, draw a dashed line. 3. Choose a test point to determine which side to shade. Next Slide 1. Simplify the inequality. -2 (Don’t forget, if you multiply or divide by a negative #, invert the inequality symbol)