Answer
$-2\leq x$, $h^{-1}(x)=\sqrt{x}-2$.
Work Step by Step
To make the function one-to-one, according to the graph, we can restrict its domain to $-2\leq x$. If we want to get a formula for the inverse function, we swap $x$ and $y$ and solve for $y$. Hence, after swapping $x$ and $y$, we get:
$x=(y+2)^2\\\sqrt x=y+2\\y=h^{-1}(x)=\sqrt{x}-2$
