Answer
$(x-6)(x-6)$
Work Step by Step
Recall:
$x^2+bx+c=(x+d)(x+e)$ where $b=d+e$ and $c=d\cdot e$.
The given trinomial has $b=-12$ and $c=36$.
Note that:
$36=(-6)(-6)$
and
$-12=-6+(-6)$.
This means that $d=-6$ and $e=-6$.
Hence, the factored form of the given trinomial is:
$$x^2-12x+36=(x-6)(x-6)$$
