y = +/- [√x+4) ] / 3
Explanation:
1) To find the inverse of the function y = 9x^2 - 4, exhange the variables x and y, and then solve for the new y.
2) Exchange of the variables: y = 9x^2 - 4 → x = 9y^2 - 4
3) Solve for y:
9y^2 = x + 4
y^2 = [x + 4] / 9
y = +/- [ √ (x + 4) ] / 3