Question 894820
They serve inverse purposes.


Look at the graph of {{{10^x=y}}}.  If x and y switch places in the equation, then this becomes the inverse.  Also, the graph will be a reflexion around the line y=x.  This gives you {{{y=log(10,x)}}}.  More, {{{10^(log(10,x))=x}}}, and also, {{{log(10,(10^x))=x}}}.