There isTe one "proof" thereof at the moment, but it is not really a proof, unless youcourse assumeassumes differentiability of the inverse, and in showing differentiability of the inverse you will have found the derivative, so anyis suchmore argumentuseful isas an aide memoire unnecessarythan a proof. I mayhave adjustmade thesome wordingslight slightlyadjustments here.and Someadded a statement about the differentiability of the inverse which would seem to be required.
