Answer
$(-\infty,-5)\cup(-5,\infty)$
Work Step by Step
The denominator of the given function, $
f(x)=\dfrac{x^2-25}{x+5}
,$ cannot be $0$. Hence,
\begin{array}{l}\require{cancel}
x+5\ne0
\\\\
x\ne-5
.\end{array}
Hence, the domain is $
(-\infty,-5)\cup(-5,\infty)
.$
