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9.5 Worksheet #2
Quadratic Formula
6) 2x2 + 3x – 20 = 0
7) 4b2 + 8b + 7 = 4
8) 2m2 – 7m – 13 = –10
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5) x2 + 4x + 3 = 0
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4) 2x2 – 3x – 5 = 0
ANSWERS 1–8:
1) m = 7 or –2 2) b = 2
3) 2m2 + 2m – 12 = 0
3) m = 2 or –3 4) x = 2.5 or –1 5) x = –1 or –3 6) x = 2.5, or –4 7) b = –0.5, or –1.5 8) m = 3.9 or –0.4
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1) m2 – 5m – 14 = 0
2) b2 – 4b + 4 = 0
11) 2k2 + 9k = –7
12) 5r2 = 80
13) 2x2 – 36 = x
14) 5x2 = –4 – 9x
15) k2 – 31 – 2k = –6 – 3k2 – 2k
16) 9n2 = 4 + 7n
17) For the period 1971–2001, the number of films produced y in the world can be modeled by the function
y = 10x2 – 94x + 3900 where x is the number of years since 1971. In what year were 4,700 films produced?
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10) x2 + 2x – 1 = 2
ANSWERS 9–19:
9) x = 4 or –2.5 10) x = 1 or –3 11) k = –1 or –3.5 12) r = ± 4 13) x = 4.5 or –4 14) x = –0.8 or –1
15) k = ± 2.5 16) n = 1.16 or –0.38 17) the year 1985
9) 2x2 – 3x – 15 = 5