Answer
$\frac{x+6}{x-6}$; $x \ne -6, 6$
Work Step by Step
To begin with, we will need to factor the numerator and the denominator. The numerator is a perfect square trinomial and the denominator is a difference of squares.
$\frac{(x+6)(x+6)}{(x+6)(x-6)}$
Here, we can see that the $x + 6$ factors cancel out. As a result, we are left with $\frac{x+6}{x-6}$. This still will only hold true as long as we include our domain restrictions from earlier. This means that we must set the original denominator equal to 0:
$(x+6)(x - 6) = 0$
This means that $x = 6$ and $x = -6$ are both domain restrictions.