Answer
$-4(x-1)(x+1)$
Work Step by Step
Factor out $-4$ to obtain:
$=-4(x^2-1)$
The binomial is a difference of two squares.
RECALL:
A difference of two squares can be factored using the formula:
$a^2-b^2=(a-b)(a+b)$
Factor the difference of two squares using the formula above with $a=x$ and $b=1$ to obtain:
$=-4(x-1)(x+1)$
