How do you factor $5 x^{3} - 10 x^{2} - 125 x$ $5x^3 -10x^2 - 125x$ ?

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Answer 1 · 2015-05-23T19:45:32

$5 x^{3} - 10 x^{2} - 125 x$ $5x^3-10x^2-125x$

$= 5 x (x^{2} - 2 x - 25)$ $=5x(x^2-2x-25)$

$= 5 x (x^{2} - 2 x + 1 - 26)$ $=5x(x^2-2x+1-26)$

$= 5 x ({(x - 1)}^{2} - {\sqrt{26}}^{2})$ $=5x((x-1)^2 - sqrt(26)^2)$

$= 5 x (x - 1 - \sqrt{26}) (x - 1 + \sqrt{26})$ $=5x(x-1-sqrt(26))(x-1+sqrt(26))$

by completing the square and by using the identity $a^{2} - b^{2} = (a - b) (a + b)$ $a^2-b^2 = (a-b)(a+b)$

Answer 2 · 2015-05-23T21:55:53

$f (x) = 5 x (x^{2} - 2 x - 25)$ $f(x) = 5x(x^2 - 2x -25)$

The trinomial in parentheses can't be factored because its D = b^2 - 4ac = 4 + 100 = 104 isn't a perfect square.

How do you factor 5x3−10x2−125x5x^3 -10x^2 - 125x?