Hello! My question is as follows:

f(x) = (x-3)^3 , x>3

Find f^-1(f(x)) and f(f^-1(x)), stating clearly the rules and domains.

I know that the rules of both are the same: f^-1(f(x)) = x and f(f^-1(x)) = x. However, I don't understand why are the domains different? Please explain to me! Thank you!