# How do you solve e^-x = 9?

Nov 29, 2016

I got: $x = - \ln \left(9\right) = - 2.19722$

#### Explanation:

We can take the natural log of both sides:
$\ln \left({e}^{-} x\right) = \ln \left(9\right)$
where the $\ln$ and $e$ cancel and you are left with:
$- x = \ln \left(9\right)$
and so:
$x = - \ln \left(9\right) = - 2.19722$