Example ELF.CELF.1 $b=3; f(x) = \exp_3(x) = 3^x$ and $g(x)=\log_3(x)$.

 $f(x) = \exp_3(x)=3^x$ $g(x) = \log_3(x)$

Martin Flashman, Jan. 10, 2014. Created with GeoGebra

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Notice how the arrows on the mapping diagrams are paired with the points on the graph of the functions.
You can move the point for $x$ on the mapping diagram to see how the function value for the function $f(x) = \exp_3(x) =3^x$ changes both on the diagram and on the graph.

Uncheck the upper box to hide the graph and arrows on the diagram for the function $f(x) = \exp_3(x) =3^x$.
Check the middle box to show the graph and arrows on the diagram for the function $g(x) = \log_3(x)$.
Leave the upper box checked to see some of the symmetry between the graphs and mapping diagrams of these two functions.
Check the lower box to show the confirmation that the paired data do satisfy the equation: $\exp_3(\log_3(y)) = y$ for all $y \in (0,\infty)$.