I need help differentiating this question:

Question

3e^-4x
that's three e to the power of negative 4x.

when you differentiate, you get:

-12e^-4x

thanks, but how come it's not -12e^-4x-1, or do i just not minus a one when the power is a co-efficient?

Remember, the differential of e^x is also e^x. So, the final answer is e^xdx. That is, you just differentiate what's in the exponent. In your case, the differential of what's in the exponent is -4, so the final answer is just -4 x the original, or -4 x (3e^-4x).