Chapter 6 - Section 6.1 - Rational Expressions and Functions; Multiplying and Dividing - Exercise Set - Page 413: 10

All real numbers apart from $2$ and $-4$.

We know that for rational expressions the domain is all the real numbers, excluding when the denominator is $0$. Here the denominator is $0$, when $x=2$ and $x=-4$, thus the domain is all real numbers apart from $2$ and $-4$.