Solution
= Solution
Taking the <conjugate transpose> of $MM^{-1}=I$ and $M^{-1}M=I$ reverses the product order and gives
$$
(M^{-1})^\dagger M^\dagger=I,\qquad M^\dagger(M^{-1})^\dagger=I.
$$
Thus $(M^{-1})^\dagger$ is the two-sided <matrix inverse> of $M^\dagger$, proving
$$
\boxed{(M^\dagger)^{-1}=(M^{-1})^\dagger.}
$$