To find the inverse of a function, you swap the x and y and then solve for y.
So, if f(x) = 1/3x^2 - 6 + 5, you start by replacing f(x) with y, to get y = 1/3x^2 - 6 + 5.
Then, swap x and y to get x = 1/3y^2 - 6 + 5.
Finally, solve for y to find the inverse function.