Mr. Vizza's Class

Solving Linear Inequalities in Two Variables


Steps

Examples Done by Mr. Vizza

Problems You Should Try

Additional Supportive Links


Steps

Step 1. Graph the given inequality as if it were an equation using the slope intercept form. If the inequality is > or <, use a dotted line. If the inequality is > or <, use a solid line.

Step 2. Pick a "test point" that is not on the line you graphed in step 1 and plug it into the given inequality. Simplify both sides of the statement.

Step 3. If the test point yields a true statement, shade the side of the line that contains the test point. If the test point yields a false statement, shade the opposite side of the line to the side that contains the test point.

 

wpe1.jpg (2600 bytes)


Examples Done by Mr. Vizza

Directions: Please solve the following linear inequality.

2x-3y<9

Step 1. Graph the given inequality as if it were an equation using the slope intercept form. If the inequality is > or <, use a dotted line. If the inequality is > or <, use a solid line.

 

 

2x-3y<9

-3y<-2x+9

y>2/3*x-3

Get the statement in y=mx+b form.

Flip the symbol, because you divide by a negative.

Put a dot on –3 on the y axis then apply a slope of 2/3.

Connect the dots with a dotted line.

Step 2. Pick a "test point" that is not on the line you graphed in step 1 and plug it into the given inequality. Simplify both sides of the statement.wpe1.jpg (2600 bytes)

 

2(0)-3(0)<9

0–0<9

0<9 TRUE

Use (0,0) as a test point.

Step 3. If the test point yields a true statement, shade the side of the line that contains the test point. If the test point yields a false statement, shade the opposite side of the line to the side that contains the test point.

wpe1.jpg (2600 bytes)

   

Because (0,0) yielded a true statement, we need to shade the side of the line that contains (0,0).


Problems You Should Try

Directions: Please solve the following linear inequalities.

1. 2.
3. 4.
5. 6.
7. 8.
9. 10.

Additional Supportive Links

 

©2004 Thomas Vizza