x² - 3x - 18 < 0
(x - 6)(x + 3) < 0
The critical numbers are 6 and -3
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-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
test value -4: (-4)² - 3(-4) - 18 < 0
16 + 12 - 18 < 0
10 < 0
False do not shade (-infinity,-3)
test value 0: (0)² - 3(0) - 18 < 0
0 + 0 - 18 < 0
-18 < 0
True, so shade (-3,6)
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-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
test value 7: (7)² - 3(7) - 18 < 0
49 -21 - 18 < 0
10 < 0
False do not shade (6, infinity)
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-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Answer (-3,6)
Edwin
