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Question 799565: For what values of x is the quantity (x−9)(x+7) negative? Enter your answer as an inequality.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! For what values of x is the quantity (x−9)(x+7) negative? Enter your answer as an inequality.
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Draw a number line.
x = 9 or x = -7 make the product be zero.
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Plot x = -7 and x = 9 on the number line.
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Test a value in each of the resulting intervals to
see where (x-9)(x+7) < 0
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Testing x = -10;; -*- < 0 :::: false
Testing x = 0 :: -*+ < 0 :::: true, so solutions in (-7,9)
Testing x = 10 :: +*+ < 0 :::: false
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Answer:: -7< x < 9
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Cheers,
Stan H.
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