# What is the derivative of e^(-x)?

$- {e}^{-} x$
then $\frac{d}{\mathrm{dx}} \left({e}^{-} x\right) = {e}^{-} x . \frac{d}{\mathrm{dx}} \left(- x\right) = {e}^{-} x . \left(- 1\right) = - {e}^{-} x$