Answer
$4(3x+2)(x-2)$
Work Step by Step
For the polynomial
$$
12x^2 -16x - 16=4(3x^2 -4x - 4)
$$
we check the factors of $ac=3(-4)=-12$. The only factors that can give the right middle term are $-6$ and $2$, as follows
$$
12x^2 -16x - 16=4(3x^2 -4x - 4)=4(3x+2)(x-2)
.$$
