The function is .
Consider the horizontal line is .
Graph:
\Graph the function for and the horizontal line is
.
\
The horizointal line touches the graph of the function at only one point.
Hnece the function pass the horizontal line test then the function is an one-to-one function.
\The inverse of the function exist.
\The function is .
The domain of the function is .
And the range of the function is .
Consider and simplify the function
in terms of
.
Replace the terms and
in the above function.
The function and its inverse are same.
\hence the domain and range of the functions are also same.
\Therefore there is not necessary to restrict the domain of the function .