3.3 SOLVING INEQUALITIES USING MULTIPLICATION OR

DIVISIONI can use multiplication or division

to solve inequalities.

Multiplication and Division Properties of Inequality

If you multiply or divide each side of an inequality by the same positive number, the direction of the inequality symbol remains unchanged.

Multiplication and Division Properties of Inequality

If you multiply or divide each side of an inequality by the same negative number, the direction of the inequality symbol is reversed.

Why it Works! Multiplying or dividing each side by a negative

number changes the meaning of the inequality. EX: 3 > 1

True? Yes!

Multiply by -2: 3(-2) > 1(-2) -6 > -2

True? No!

What if I reverse the symbol? -6 < -2

True now? Yes!

Practice

-3y ≤ -27

y ≥ 9

Application You walk dogs in your neighborhood after

school. You earn $4.50 per dog. How many do you need to walk to earn at least $75?

Divide by 4.50: d ≥ Round up to 17 since d represents the

number of dogs. You must walk at least 17 dogs to make at

least $75.

Assignment

Odds Only P. 181 #7-31