Respuesta :
[tex]y = \ln (5x)\\
e^y=5x\\
x=\dfrac{e^y}{5}\\
\boxed{f^{-1}(x)=\dfrac{e^x}{5}}[/tex]
[tex]f(x)=\ln5x\\\\\ln5x=y\\\\e^{\ln5x}=e^y\iff5x=e^y\ \ \ |divide\ both\ sides\ by\ 5\\\\x=\dfrac{e^y}{5}\\\\\boxed{f^{-1}(x)=\dfrac{e^x}{5}}[/tex]