Beginning Algebra, 11th Edition

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        34. 35.Concept Check When a student was asked to solve , she wrote as her
            answer. Her teacher did not give her full credit. The student argued that because
            , her answer had to be correct.WHAT WENT WRONG?Give the correct
            solution set.
            36.Explain the square root property for solving equations, and illustrate with an example.
        
        
        
        
    
    
    
    

92 = 81

x^2 = 81 596

3 x^2 + 8 = 80 - 8 x^2 =- 64 - 12 x^2 =- 144

5 x^2 + 4 = 8 4 p^2 - 3 = 7 2 t^2 + 7 = 61

3 p^2 = 10 3 n^2 - 72 = 0 5 z^2 - 200 = 0

r^2 - 3 = 0 x^2 - 13 = 0 7 x^2 = 4

m^2 = x^2 =2.25 w^2 =56.25

36

121

558 CHAPTER 9 Quadratic Equations

Solve each equation by using the square root property. Simplify all radicals. See Examples 3 –5.

55.Jeff solved the equation in Exercise 47and wrote his answer as ,. Linda

solved the same equation and wrote her answer as ,. The teacher

gave them both full credit. Explain why both students were correct.

56.In the solutions found in Example 4of this section, why is it not valid to sim-

plify the answers by dividing out the 3’s in the numerator and denominator?

2  323

3

• 5 - 230
  
  
  • 2
    e-^5 +^230 f
  
  
  
  


• 2

5 - 230

e 2 f

5 + 230

2

a 14 x- 122 - 48 = 0 12 x- 522 - 180 = 0

1

3

m+ 4 b

2

= 27

a

1

2

x+ 5 b

2

13 k+ 122 = 18 15 z+ 622 = 75 = 12

17 z- 522 = 25 15 - 2 x 22 = 30 13 - 2 x 22 = 70

13 x+ 222 = 49 15 t+ 322 = 36 14 x- 322 = 9

1 m+ 222 =- 17 1 x- 822 = 27 1 p- 522 = 40

1 x- 322 = 25 1 x- 722 = 16 1 z+ 522 =- 13

Use a calculator with a square root key to solve each equation. Round your answers to the

nearest hundredth.

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58. 1 2.11p+3.42 22 =9.58 60. 1 1.71m-6.20 22 =5.41

1 k+2.14 22 =5.46 1 r-3.91 22 =9.28

Solve each problem. See Example 6.

61.One expert at marksmanship can hold a silver dollar

at forehead level, drop it, draw his gun, and shoot the

coin as it passes waist level. The distance traveled by

a falling object is given by

where dis the distance (in feet) the object falls in

tseconds. If the coin falls about 4 ft, use the formula

to estimate the time that elapses between the drop-

ping of the coin and the shot.

d= 16 t^2 ,

d

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