Answer
-5
Work Step by Step
A natural logarithm is a logarithm to base $e$. As shown on page 582, when a natural logarithm is written in the form $ln (x)$, this is equivalent to the expression $log_{e}x$.
Therefore, $ln (e^{-5})=log_{e}e^{-5}=-5$. We know this, because $(e)^{-5}=e^{-5}$.
