Should I use the theorem: $S,T$ linear transformations in $\mathbb R^n$ such that $ST=TS$ $\implies e^{S+T}=e^Se^T$ to prove $e^{-T}=(e^T)^{-1}$?
My professor suggested to apply the mentioned theorem, but I don't see how to apply it.
Can someone give a hint?
Thnks in advance.