The function is
.
The function
is one-to-one for
.
The function is
.
Rewrite the function as
.
Find the inverse function.
\
.
Interchange the variables
and
.

Substitute
.
.
The inverse of the function is
.
The inverse function is
.
The domain of a function is all values of
, those makes the function mathematically correct.
The radicand should be greater than or equals to zero.
\
Thus, the domain of
is
.
The inverse function is
and its domain is
.