Page 167 - Basic College Mathematics with Early Integers

144 C HAPTE R 2 I INTEGERS AND INTRODUCTION TO VARIABLES

PRACTICE 9 Example 9 Evaluate: -7 2
Evaluate: -9 2
Solution: Remember that without parentheses, only the 7 is squared.
2
#
-7 =-17 72 =-49
Work Practice 9

Make sure you understand the difference between Examples 8 and 9.
parentheses, so -5 is squared
2
2
1-52 = 1-521-52 = 25
no parentheses, so only the 7 is squared
#
2
-7 =-17 72 =-49

Objective Dividing Integers

Division of integers is related to multiplication of integers. The sign rules for divi-
sion can be discovered by writing a related multiplication problem. For example,
6
#
= 3 because 3 2 = 6
2 Just as for whole
-6 numbers, division of integers can
#
= -3 because -3 2 =-6
2 be checked by multiplication.
6
#
= -3 because -3 1-22 = 6
-2
-6
#
= 3 because 3 1-22 =-6
-2
Dividing Numbers
The quotient of two numbers The quotient of two numbers
having the same sign is a positive having different signs is a negative
number. number.
Quotient of Like Signs Quotient of Different Signs

1+2 1-2 1+2 1-2
=+ =+ =- =-
1+2 1-2 1-2 1+2

PRACTICE 10–12 Examples Divide.
Divide. -12
10. =-2
28 6
10. 11. -18 , 1-22
-7 11. -20 , 1-42 = 5
-60 48
12. 12. =-16
10 -3
Work Practice 10–12
Answers
9. -81 10. -4 11. 9 12. -6 Copyright 2012 Pearson Education, Inc.
Concept Check What is wrong with the following calculation?
Concept Check Answer
-27
-27 =-3
= 3 -9
-9