1. Warm Up
Solve.
1. x + 5 = 9
2. x – 34 = 72
= x – 39
x = 4
x = 106
x = 163

2. Learn to solve one-step equations by using multiplication or division.

3. Vocabulary
Multiplication Property of Equality – you can multiply both sides of an equation by the same number and the statement will still be true
Division Property of Equality – you can divide both sides of an equation by the same number and the statement will still be true

4. • 2 5 10 = 10 5 2 ÷ = Like addition and subtraction, multiplication
and division are inverse operations. They
“undo” each other. 2 • 5 10 = 10 5 2 ÷ =

5. If a variable is divided by a number, you can often use multiplication to isolate the variable. Multiply both sides of the equation by the number.

6. Additional Example 1: Solving an Equation by Multiplication
Solve the equation = 13. Check your answer. h 2 h 2
= 13 h 2
(2)
= 13(2)
Think: h is divided by 2, so
multiply both sides by 2 to
isolate h.
h = 26
Check h 2
= 13 26 2 ?
= 13
Substitute 26 for h.
13 = 13 ?
26 is a solution. 

7.  Check It Out: Example 1 Solve the equation = 30. Check your answer.5
Solve the equation = 30. Check your answer. x 5
= 30 x 5
(5)
= 30(5)
Think: x is divided by 5, so
multiply both sides by 5 to
isolate x.
x = 150
Check x 5
= 30
150 5 ?
= 30
Substitute 150 for x.
30 = 30 ? 
150 is a solution.

8. You cannot divide by 0.
Remember!

9. If a variable is multiplied by a number, you can often use division to isolate the variable. Divide both sides of the equation by the number.

10. Additional Example 2: Solving an Equation by Division
Solve the equation 51 = 17x. Check your answer.
51 = 17x
Think: x is multiplied by 17,
so divide both sides by 17 to
isolate x.
51 = 17x 17 17
3 = x
Check
51 = 17x
51 = 17(3) ?
Substitute 3 for x.
51 = 51 ? 
3 is a solution.

11. Check It Out: Example 2
Solve the equation 76 = 19y. Check your answer.
76 = 19y
Think: y is multiplied by 19,
so divide both sides by 19 to
isolate y.
76 = 19y 19 19
4 = y
Check
76 = 19y
76 = 19(4) ?
Substitute 4 for y.
76 = 76 ? 
4 is a solution.

12. Homework
Page 58
#8-18 Even Only

13. Lesson Quiz: Part I
Solve the equation. Check your answer.
1. 12 = 4x
2. 18z = 90
3. 12 =
= 12y 5.
x = 3; 12 = 4  3
z = 5; 18  5 = 90 x 4
x = 48; 12 = x 4
y = 70; 840 = 12  70 h 22
h = 198; = 9
198 22
= 9