Thread: Inverse function

If f(x) = ln 4x, what is the value of f^-1(6). (The f raises to the -1 is the inverse function of f(x).

The answer is 100.86.

So, let y = ln(4x). How, in general, do you invert functions?

The natural log (ln) has a base e, so another way of rewriting f(x) = ln 4x or y = ln 4x:



y = 6. Substituting it into this equation and solving for x will yield approximately 100.86.