Beginning Algebra, 11th Edition

93.Concept Check Which one of these rational expressions is notequivalent to?

A. B. C. D.

94.Concept Check Make the correct choice for the blank: and

equivalent rational expressions. (are/are not)

Write four equivalent forms for each rational expression. See Example 7.

95. 
    
    
    
    96. 
        
        
        
        97. 
            
        
        
        
        
    
    
    
    


96. 
    
    
    
    99. 100.-
        2 x- 9
        7 x- 1
    
    
    
    

• 3 x- 1
  5 x- 6


• 
  

  5 x- 6
  x+ 4

  
  


• 
  

  2 x- 3
  x+ 3

  
  


• 
  

  x+ 6
  x- 1

  
  


• 
  

  x+ 4
  x- 3

  
  


• 5 - 2 x
  x- 3

5 + 2 x

3 - x

x- 3

x- 4

3 - x

4 - x

x+ 3

4 +x

3 - x

x- 4

x- 3

4 - x^

428 CHAPTER 7 Rational Expressions and Applications

101.The area of the rectangle is represented

by

.

What is the width? Hint:Use

102.The volume of the box is represented by

.

Find the polynomial that represents the

area of the bottom of the box.

1 x^2 + 8 x+ 1521 x+ 42

W= B

a

A L^.

x^4 + 10 x^2 + 21

x^2 + 7

x + 5

Solve each problem.

103.The average number of vehicles waiting in line to enter a sports arena parking area is

approximated by the rational expression

,

where xis a quantity between 0 and 1 known as the traffic intensity.(Source:Mannering,

F., and W. Kilareski, Principles of Highway Engineering and Traffic Control,John Wiley

and Sons.) To the nearest tenth, find the average number of vehicles waiting if the traffic

intensity is the given number.

(a)0.1 (b)0.8 (c)0.9

(d)What happens to waiting time as traffic intensity increases?

104.The percent of deaths caused by smoking is modeled by the rational expression

where xis the number of times a smoker is more likely than a nonsmoker to die of lung

cancer. This is called the incidence rate.(Source:Walker, A., Observation and Infer-

ence: An Introduction to the Methods of Epidemiology,Epidemiology Resources Inc.)

For example, means that a smoker is 10 times more likely than a nonsmoker to

die of lung cancer. Find the percent of deaths if the incidence rate is the given number.

(a) 5 (b) 10 (c) 20

(d)Can the incidence rate equal 0? Explain.

x= 10

x- 1

x

,

x^2

211 - x 2

Multiply or divide as indicated. Write each answer in lowest terms. See Section 1.1.

7

12

,

15

4

10

3

,

5

6

3

7

#^4

5

2

3

#^5

6

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