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LESSON 3.6 DAY 2
Solving Inequalities Using Addition or Subtraction
Goal: Solve inequalities using addition or subtraction.
Warm-up:
Solve the following equations. CHECK your solution!
1) m – 3 = 8
2) x – 9 = -14
3) 6 + a = 13
4) What does it mean when two expressions are equal?
5) Describe a real life application where an inequality would make more sense than an equation.
6) Do you think that solving an inequality might be related to solving an equation? Explain.
Addition and Subtraction Properties of Inequality
Words Adding or subtracting the same number on each side of an inequality produces an equivalent
inequality.
Algebra If a  b, then a + c ______+ c.
If a  b, then a –_______ b – c.
EXAMPLE 1 - Solving and Graphing Inequalities
Solve the inequality. Then graph its solution.
a.
m–38
When you number a number line….you don’t have to label every line but number all the way across!
Also…you must label the point that you graph with a number if it is not already labeled.
b.
x – 9 ≥ –14
c.
6 + a  13
Now You Try It!
Solve the Inequality. Then graph its solution.
1. y – 7 ≤ –2
2.
4  t – 10
3.
15 ≥ z + 18
4.
7.5 + r  3
EXAMPLE 2 - Writing and Solving an Inequality
Shopping You want to buy a DVD player that costs $89. You have $110 to spend. You also want to
buy a DVD. What can the cost of the DVD be in order for you to buy both the DVD player and the
DVD?