Reverse Error

9 ^(1/2) = 3 9^(?) =1/3 how do you do a reverse log without trial and error?

I should have asked a question in math class

log(1/x) = -log(x) or
x^(-a) = 1/(x^a)

So, if 9^(1/2) = 3, then 9^(-1/2) = 1/3

「REVERSE±ERROR」歌ってみました。【のある】