1. Using the Quadratic Formula
ALGEBRA 1 LESSON 10-7
pages 550–552  Exercises
1. –1, –1.5
2. 2.8, –6
3. 1.5
4. –0.67, –15
, –0.25
6. –4, –9
, –16
8. 13, –8.5
9. 16, –2.4
, –2.67
, 1.58
, –0.77
, –3.03
, –0.17
16. a. 0 = –16t t + 3
b. t ; 0.8 s
17. a. 0 = –16t t + 3.5
b. t ; 3.2 s
18. Completing the square or graphing;
the x2 term is 1 but the equation is not factorable.
19. Factoring or square roots; the equation
is easily factorable and there is no x term.
20. Quadratic formula; the equation
cannot be factored.
21. Quadratic formula; the equation
22. Factoring; the equation is easily factorable.
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2. Using the Quadratic Formula
ALGEBRA 1 LESSON 10-7
34. About 2.1s
35. Answers may vary. Sample: You solve
the linear equation using transformations
and you solve the quadratic equation
using the quadratic formula.
ft and 5.40 ft
cm and 7.44 cm
38. Answers may vary. Sample: A rectangle
has length x. Its width is 5 feet longer
than three times the length. Find the
dimensions if its area is 182 ft2.
7 ft  26 ft
23. Quadratic formula;
the equation cannot be factored.
24. 6, –6
, –1.54
, –1.41
, –2.61
28. 2
29. 3, –3
, –0.39
, –1
, –1.43
33. a. 7 ft  8 ft
b. x(x + 1) = 60, 7.26 ft  8.26 ft
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3. Using the Quadratic Formula
ALGEBRA 1 LESSON 10-7
53. (6v – 5)(2v + 7)
54. (2x – 1)(3x – 5)
55. (5t + 3)(3t + 2)
39. if the expression b2 – 4ac
equals zero
40. about 1.9 s
41. a. Check students’ work.
b million
c. 2007
42. a. s = –
b. 6.5
46. [2]
–1.8, 3.7
[1] correct substitution into
quadratic formula,
with one calculation error
, 8.46
48. –1, –2
, –6.1
50. (2c + 5)(c + 3)
51. (3z – 2)(z + 4)
52. (5n + 2)(n – 7)
11 ± (112) – 4(6)(–40)
2(6)
x = a b
43. a  107 lb
b. 3.3  104 tons
c s
44. D
45. F
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