Find the domain of the rational

The domain means the values of x that are allowed. In the case of rational expressions, that is all values that don't result in division by zero.

x - 7

-------------

x

^{2 }- 4x - 12 x - 7

= ----------------

(x - 6) (x + 2)

The domain is all values of x except for -2 and 6.