The function is and the interval is
.
Consider .
Differentiate on each side with respect to .
Apply property : .
Since the function is a piecewise function, it is undefined at
.
on
.
Therefore is increasing and thus has an inverse on this interval.
is positive on the domain of
.
is strictly monotonic and it must have an inverse function.
is monotonically increasing on the interval
, so it must have an inverse function on the interval.