How do you write ##3^2=9## in logarithmic form?

It is ##log_3 9=2##

By definition the logarithmic form ##log_b x=y## is equivalent to the exponential form ##b^y=x##

Hence from the given ##3^2=9## you have ##b=3## ,##y=2## , ##x=9##

hence the logarithmic form is ##log_3 9=2##