## Precalculus (10th Edition)

$\ln{M}=2.2$
We know that: (1) if $a^x=y$, then $\log_a y=x$; and (2) $\log_e{x}=\ln{x}$. Hence if $e^{2.2}=M$, then \begin{align*} \log_e{M}=2.2\\ \ln{M}=2.2 \end{align*}