Chapter 4 - Polynomial and Rational Functions - 4.2 Properties of Rational Functions - 4.2 Assess Your Understanding - Page 197: 17

All real numbers except $-4$ and $2$.

The denominator of a rational cannot be $0$. Note that when $x=2$ or $x=-4$, the denominator of the given function will be equal to zero. Therefore, the domain of the given function is the set of all real numbers except $-4$ and $2$.