Why is a function f (x) equal to the LNF (x) power of E

Why is a function f (x) equal to the LNF (x) power of E

Can this be equal to? Of course not!
If f (x) > 0!
prove:
Let y = LNF (x)
Then: e ^ y = f (x)
So: e ^ (LNF (x)) = f (x)