Question

Which function below is the inverse of f(x) = x2 − 25?

Answer 1

(x-5)(x+5) is the answer

Answer 2

$f(x) = x^{2} - 25$  can be written as $y = x^{2} - 25$

when finding inverse the first step is to interchange x and y in the equation

∴ $(x) = (y)^{2} - 25$

then you simply solve for y

$x + 25 = y^{2}$

$y = \sqrt{ (x + 25)}$

Thus $f^{-1} (x) = \sqrt{(x + 25)}$