Question 894839: Given f(x)=-x^3+7x^2-9x-5 & that x=5 is a root, find the other roots. (Find the depressed equation, then use the quadratic formula). Simplify your answer as much as possible, but do not approximate with decimals.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Given f(x)=-x^3+7x^2-9x-5 & that x=5 is a root, find the other roots. (Find the depressed equation, then use the quadratic formula). Simplify your answer as much as possible, but do not approximate with decimals. -----
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Using synthetic division::
5)....-1....7....-9....-5
......-1....2.....1...|..0
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Quotient:: -x^2 + 2x + 1
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Using the quadratic formula::
x = [-2 +- sqrt(4 - 4*-1*1)]/-2
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x = [-2 +- sqrt(8)]/(-2)
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x = [-2+-2sqrt(2)]/(-2)
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x = 1 +- sqrt(2)
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Cheers,
Stan H.
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