Page 603 - Basic College Mathematics with Early Integers

580 C HAPTE R 8 I INTRODUCTION TO ALGEBRA

Check: We replace y with -3.
3y - 7y = 12

b T

31-32 - 71-32 12
-9 + 21 12
12 12 True
The solution is -3.
Work Practice 6

PRACTICE 7 Example 7 Solve: -2z + z = 11 - 5
Solve: -3a + 2a =-8 + 6
Solution: We simplify both sides of the equation first.
-2z + z = 11 - 5
-1z = 6 Combine like terms.
-1z 6
= Divide both sides by -1.
-1 -1
z =-6 Simplify.
Check to see that -6 is the solution.

Work Practice 7

z
PRACTICE 8 Example 8 Solve: = 11 - 5
-4
a
Solve: -8 + 6 = Solution: Simplify the right side of the equation first.
3
z
= 11 - 5
-4
z
= 6
-4
Next, to get z alone, multiply both sides by -4 .
z
#
-4 # =-4 6 Multiply both sides by -4 .
-4
-4
#
# z =-4 6
-4
1z =-24 or z =-24
Check to see that -24 is the solution.
Work Practice 8

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Answers
7. 2 8. -6