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.