Answer
$$y=\frac{9-66x+121x^2}{1+2x+x^2}$$
Work Step by Step
Switching the elements of the domain and the range (in other words, the dependent and independent variables), we find that the inverse is:
$$x=\frac{\sqrt{y}+3}{11-\sqrt{y}} \\ y=\frac{9-66x+121x^2}{1+2x+x^2}$$