Answer
$$y=\frac{5\sqrt{x}}{4},\:y=-\frac{5\sqrt{x}}{4}$$
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:
$$x=\frac{16}{25}y^2 \\ y=\frac{5\sqrt{x}}{4},\:y=-\frac{5\sqrt{x}}{4}$$
