Chapter 2 - 2.2 - Functions - 2.2 Exercises - Page 183: 51

All real numbers except {0,-2}.

$g(x)=1/x - 3/(x+2)$ Eliminate the values that make the denominator zero, hence x=0 and x=-2 are not in the domain. All other real numbers are valid. Hence the domain is all real numbers except x=0 and x=-2.