Answer
The domain is all real numbers except for $-6$ and $3$.
Work Step by Step
In order to find when the given function exists, we have to find out when it is undefined. For a function to be defined, the denominator can never be zero. Thus, we can see when the denominator of the fraction is equal to $0$.
$x^2+3x−18 = 0 \\ (x+6)(x−3) = 0 \\ x = -6,3$
Thus, the domain is all real numbers except for $-6$ and $3$.
