Answer
$ f^{-1}(x)=\frac{x}{3}$
Work Step by Step
We are given the function, $f(x)=3x$. First, we must replace $f(x)$ with y.
$y=3x$
Next, interchange x and y.
$x=3y$
Next, solve for y by dividing both sides by 3.
$y=\frac{x}{3}$
Finally, replace y with $f^{-1}(x)$.
$ f^{-1}(x)=\frac{x}{3}$
