$$y = x ^ { 2 } - 4 x - 12$$
$x=\sqrt{y+16}+2$
$x=-\sqrt{y+16}+2$
$x=\sqrt{y+16}+2$
$x=-\sqrt{y+16}+2\text{, }y\geq -16$
$y=\left(x-6\right)\left(x+2\right)$
