## Precalculus (6th Edition) Blitzer

$x(x-2)(x+2)$
Factor out $x$ to obtain: $=x(x^2-4) \\=x(x^2-2^2)$ Factor the difference of two squares using the formula $a^2-b^2=(a-b)(a+b)$ where $a=x$ and $b=2$ to obtain: $=x(x-2)(x+2)$