Sec. 3-3:Solving Inequalities Using Multiplication & Division

Again, solve inequalities the same way you solve equations…use the OPPOSITE operation.

Remember that when you are MULTIPLYING or DIVIDING by a NEGATIVE COEFFICIENT that causes your inequality sign to change.

***Always check your answers (at least mentally) to make sure they actually work!

i.e. Solve x > 8

5

***Because this problem involves division, you will solve it by MULTIPLYING by the RECIPROCAL of the COEFFICIENT….5

5 ● x > 8 ● 5

5

x > 40

i.e. Solve -3c ≥ 2

This problem involves multiplication, so we will DIVIDE by the coefficient to get rid of the -3…and it is a NEGATIVE coefficient, so the ≥ will switch to ≤.

-3c ≥ 2

-3 -3

c ≤ -2/3

**Check your answer to make sure it works!