TADM2E 2.39
From Algorithm Wiki
$ \begin{align} a^{log_a(xy)} & = xy \\ & = a^{log_a(x)} a^{log_a(y)} \\ & = a^{log_a(x) + log_a(y)} \\ \end{align} $
$ \begin{align} a^{log_a(xy)} & = xy \\ & = a^{log_a(x)} a^{log_a(y)} \\ & = a^{log_a(x) + log_a(y)} \\ \end{align} $
