Download Multiplying and Dividing Real Numbers

Name
Class
1-6
Date
Reteaching
Multiplying and Dividing Real Numbers
You need to remember two simple rules when multiplying or dividing real
numbers.
1. The product or quotient of two numbers with the same sign is positive.
2. The product or quotient of two numbers with different signs is negative.
What is the product –6(–30)?
–6(–30) = 180
–6 and –30 have the same sign so the product is positive.
What is the quotient 72 ÷ (–6)?
72 ÷ (–6) = –12
72 and –6 have different signs so the quotient is negative.
Exercises
Find each product or quotient.
1. –5(–6)
2. 7(–20)
3. –3 × 22
4. 44 ÷ 2
5. 81 ÷ (–9)
6. –55 ÷ (–11)
7. –62 ÷ 2
8. 25 · (–4)
9. (–6)2
10. –9.9 ÷ 3
1
2
13.  
11. –7.7 ÷ (–11)
2  3
1
3
14.    
3  5
12. –1.4(–2)
3  1
15. .  
4  3
16. The temperature dropped 2°F each hour for 6 hours. What was the total
change in temperature?
17. Reasoning Since 52 = 25 and (–5)2 = 25, what are the two values for the square
root of 25?
Prentice Hall Algebra 1 • Teaching Resources
Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
59
Name
Class
1-6
Date
Reteaching (continued)
Multiplying and Dividing Real Numbers
The product of 7 and
1
is 1. Two numbers whose product is 1 are called
7
reciprocals. To divide a number by a fraction, multiply by its reciprocal.
What is the quotient
To divide by a fraction, multiply by its reciprocal.
2  5
2  7
      
3  7
3  5

2  5
  ?
3  7
The signs are different so the answer is negative.
14
15
Exercises
Find each quotient.
1
2
18 
1
1
3
 1
21.    
2  4
19. 6 
2  2
2
3
 5
20.     
5  3
 1
22.       
 7   2
2
3
23.  
1
4
1
a
24. Writing Another way of writing is a ÷b Explain how you could evaluate 2
1
b
6
What is the value of this expression?
Prentice Hall Algebra 1 • Teaching Resources
Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
60