Answer
The domain of $R(x)$ is the set of all real numbers $x$ except $-3$.
In set notation: $\text{Domain:} \{x|x \neq -3\}$
Work Step by Step
Rational functions are of the form
$$R(x)=\dfrac{p(x)}{q(x)}$$
The domain of the rational function is the set of all real numbers except those for which the denominator $q(x)$ is $0$.
$\text{Set the denominator equal to zero}$ then solve to obtain:
$$3+x = 0\\[3mm] x=-3$$
The domain of $R(x)$ is the set of all real numbers $x$ except $-3$.
$\text{Domain:} \{x|x \neq -3\}$
