Given the function f (x) = 3x, find the value of f-1 (81). For this case, the first thing you should do is rewrite the function. We have then: y = 3 ^ x From here, we clear the value of x: log3 (y) = log3 (3 ^ x) log3 (y) = x Then, we rewrite the function again: f (x) ^ - 1 = log3 (x) Now, we evaluate the inverse function for x = 81: f (81) ^ - 1 = log3 (81) f (x) ^ - 1 = 4 Answer: the value of f-1 (81) is: f (x) ^ - 1 = 4
