What is the value of the integral of e^x from x = 1 to x = 2?

As the derivative of e^x is e^x, so is the integral (plus some constant). As we wish to find the value of the integral from x = 1 to x = 2, we substitute x=2 into e^x, and from that we subtract e^x with x=1. The answer is therefore e^2 - e^1, or equivalently e(e - 1).