The function is .
Find an equation for the inverse function.
\Let and solve for
in terms of
.
Let .
.
Differentiate on each side with respect to .
, which is always positive for
so the function
is strictly increasing on its domain.
The domain of is
.
There is no negative terms so the function is monotonic.
is monotonic and therefore has an inverse function.
Inverse function of exists because the function
is monotonic.