Answer
$f^{-1} (x) =-3+\sqrt x$
Work Step by Step
When we apply the horizontal test, it has been noticed that the function is one-to-one and verifies the horizontal test.
Therefore, the function has an inverse function.
To compute the inverse, we will have to interchange $y$ and $x$.
$x=(y+3)^2 \implies y+3= \pm \sqrt x$
or, $y=-3 \pm \sqrt x$
Since the domain for the function is $x \geq -3$, we neglect $-3-\sqrt x$
So, we have $y=-3+\sqrt x$
Replace $y$ with $f^{-1} (x) =-3+\sqrt x$
