If you want to find an inverse function, you switch the places of the x and the y coordinates and solve for the new y. If we switch the x and y in our function we have [tex]x=8 \sqrt{y} [/tex]. We now have to "undo" that square root by squaring both sides. Doing that gives us [tex] x^{2} =64y[/tex]. Dividing both sides by 64 gives us that [tex]y= \frac{1}{64} x^{2} ,x \geq 0 [/tex], the third choice down.