inverse fcns: find inverse of y=3X-1 (i get x - 1 = 3^y)

[smash_021]

y=3X-1
x=3^y-1
x-1=3^y

solve for y
x-1=3^y as far as i can go, how do i get y by itself to get f^-1(x)

 

[pka]

Re: inverse functions

Note the +.
\(\displaystyle y = \log _3 \left( {x + 1} \right)\)
or
\(\displaystyle y = \frac{{\ln (x + 1)}}{{\ln (3)}}\)