factor: x^3+5x^2-16x-80?

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factor: x^3+5x^2-16x-80?

2007-03-31 10:07:12 · 4 answers · asked by crazy 2 1 in Science & Mathematics ➔ Mathematics

4 answers

x^2 (x+5) - 16 (x+5) = (x^2 - 16)(x+5) = (x-4)(x+4)(x+5)

Remember that: if you have this kind of expression

x^3 + ax^2 + bx + ab

you can factorize it this way

Ana

2007-03-31 10:25:36 · answer #1 · answered by MathTutor 6 · 0⤊ 0⤋

factor by groups
(3x^3 + 5x^2) + (-16x - 80)

x^2(x + 5) + -16(x+5)

(x^2 - 16) (x+5)

(x+4)(x-4)(x+5)

2007-03-31 17:11:27 · answer #2 · answered by 7 · 0⤊ 0⤋

x = 4 is a root so x-4 is a factor.
Long division gives (x^3+5x^2-16x-80)/(x-4) =x^2+9x+20
x^2+9x+20 = (x+5)(x+4)
So total factoring is (x-4)(x+4)(x+5)

2007-03-31 17:20:43 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋

no.

2007-03-31 17:10:02 · answer #4 · answered by Dave C 2 · 0⤊ 1⤋