Find the inverse function of function .

　　Solution：According to the method of finding the inverse function , let , then we have

,

so

,

It can be understood from the above

.

Change the sign of the variable to get the desired inverse function

.

　　Note: Draw the graph of the ( direct) function in this example and the inverse function sought on the same coordinate plane (see the figure below). It is easy to see the symmetry of the graph of the function and its inverse function about the straight line .