Question 236040: how do you factor x^3-4x^2-5x+20
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! factor x^3-4x^2-5x+20
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I graphed it and found a zero at x = 4.
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Use synthetic division to find the other roots.
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4)....1....-4....-5....20
.......1.....0.....-5...|..0
Quotient x^2-5
Remainder : zero
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Solve x^2-5 = 0
x = sqrt(5) or x = -sqrt(5)
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The three roots are 4, sqrt(5), -sqrt(5)
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Cheers,
Stan H.
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