Logarithms Function*

Question

This question is really confusing me:

 

If f(x) = 3^x-2, Find f(log₃a) for a>0

 

Step-By-Step would be greatly appreciated!

Answer 1

 f(x ) = 3 ^{X -2}

 

  f( X ) = 3^X / 9  = 1/9 ( 3^{X )} 

 

 f ( log₃ a ) = 1/9 ( 3 ^{log₃a )}