Question

If f(x) = 2x+4, which of the following is the inverse of f(x)?

Answer 1

By definition of inverse function,

$f\left(f^{-1}(x)\right) = x$

Given that f(x) = 2x + 4, solve for the inverse of f :

$f\left(f^{-1}(x)\right) = 2 f^{-1}(x) + 4 = x \implies f^{-1}(x) = \dfrac{x-4}2$

(I'm not entirely sure which answer that corresponds to from the choices provided...)