## Precalculus (6th Edition) Blitzer

$3x^2(x+2)(x-5)$
Factor out $3x^{2}$ $=3x^{2}(x^{2}-3x-10)$ Factoring $x^{2}+bx+c$, we search for factors (m and n) of $c$ whose sum is $b.$ If they (m and n) exist, we obtain $(x+m)(x+n)$. We see that $-5$ and $+2$ are factors of $-10$, and their sum is $-3.$ = $3x^2(x+2)(x-5)$