#1**+1 **

y = 12^{x} take the log of both sides

log y = log 12^{x} and we can write

log y = x log 12 divide both sides by log (12)

log y / log (12) = x exchange x and y

log x / log 12 = y for y.......write f^{-1} (x)

So

f^{-1}(x) = log x / log 12

Here' sthe graph of both the original function and the inverse : https://www.desmos.com/calculator/beo7z7kzbj

CPhill
Oct 16, 2017