Question

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

Answer 1

You have to use the chain rule

Explanation:

To evaluate the `(e^-x)'` you must calculate the `(e^u)' * u'`, where `u=-x`. But, `(e^u)' = e^u`, and `u'=-1`, and then:

`(e^-x)'=e^-x * (-1)= -e^-x`