Intermediate Algebra (11th edition)

Use the zero-factor property to solve each equation. (Hint: In Exercises 9 and 10, write the
equation in standard form first.)See Example 1.

5.x^2 + 3 x+ 2 = 0 6.x^2 + 8 x+ 15 = 0 7. 3 x^2 + 8 x- 3 = 0

SECTION 9.1 The Square Root Property and Completing the Square 503

8. 2 x^2 +x- 6 = 0 9. 2 x^2 = 9 x- 4 10. 5 x^2 = 11 x- 2

Use the square root property to solve each equation. See Examples 2, 4, and 5.

In Exercises 35 and 36, round answers to the nearest tenth. See Example 3.

15 t+ 222 = 12 12 - 5 t 22 = 12 11 - 4 p 22 = 24

13 x- 122 = 7 12 x- 522 = 10 14 p+ 122 = 24

1 x+ 322 = 11 1 t+ 522 = 48 1 m- 622 = 27

1 x- 622 = 49 1 x- 422 = 64 1 x- 422 = 3

5 z^2 - 200 = 0 1 x+ 222 = 25 1 t+ 822 = 9

x^2 - 20 = 0 p^2 - 50 = 0 3 x^2 - 72 = 0

x^2 = 19 x^2 = 32 x^2 = 54

x^2 = 81 x^2 = 225 x^2 = 17

35.The sculpture of American presidents at
Mount Rushmore National Memorial is
500 ft above the valley floor. How long
would it take a rock dropped from the
top of the sculpture to fall to the ground?
(Source: http://www.travelsd.com))

36.The Gateway Arch in St. Louis, Mis-

souri, is 630 ft tall. How long would

it take an object dropped from the top

of the arch to fall to the ground? (Source:

http://www.gatewayarch.com)

37.Concept Check Which one of the two equations

and

is more suitable for solving by the square root property? Which one is more suitable for

solving by completing the square?

38.Why would most students find the equation easier to solve by completing
the square than the equation?

Concept Check Decide what number must be added to make each expression a perfect
square trinomial. Then factor the trinomial.

48.Concept Check What would be the first step in solving by completing
the square?

2 x^2 + 8 x= 9

x^2 + x^2 - 0.8x+

1

2

x^2 + x+

1

4

x+

x^2 - 20 x+ q^2 + 9 q+ t^2 + 13 t+

x^2 + 6 x+ x^2 + 14 x+ p^2 - 12 p+

5 x^2 + 2 x= 3

x^2 + 4 x= 20

12 x+ 122 = 5 x^2 + 4 x=12,