# Factorizing

• Jan 24th 2009, 02:02 AM
studentme
Factorizing
Code:

`f(x) = x^3 - 3x^2 - 18x - 40`
The answer comes to f (x) = (x + 5)(x + 2)(x - 4)

Can someone please explain how this was obtained?
• Jan 24th 2009, 02:36 AM
princess_21
Quote:

Originally Posted by studentme
Code:

`f(x) = x^3-3x^2-18x - 40`
The answer comes to f (x) = (x + 5)(x + 2)(x - 4)

Can someone please explain how this was obtained?

if that is the question then the answer is wrong, or your input is wrong see:

$(x+5)(x+2)(x-4)$

$x^2+7x+10(x-4)$

$x^3+7x^2+10x-4x^2+7x^2-28x-40$

$=x^3+3x^2-18x-40$