Hi. Question - integrate the following function:

28-1-19

(int) (4 + ((e^x))^3) e^x dx

The answer is 1/4(4 + (e^x))^4 + C

doing the work myself, du = 3((4 + (e^x))^2) which means it does not fit the general power formula, because e^x is not the derivative of (4 + ((e^x))^3)

nor would it work the other way around, the derivative of e^x is e^x correct??

or can someone explain how it does? Thanks.