Answer
$f^{-1} (x)=\sqrt x-6$
Domain of the function $f$ is: $[-6, \infty)$.
Domain of the inverse of function $f$ is: $[0, \infty)$.
Work Step by Step
We have $y=(x+6)^2$
To compute the inverse, we will have to interchange $x$ and $y$.
$x=(y+6)^2$
Re-write as: $ y=\sqrt x-6$
Replace $y$ with $f^{-1} (x)$.
so, $f^{-1} (x)=\sqrt x-6$
