Given:
e^2x - e^x - 12 = 0
We are asked to find x.
Let's factor the left side of the equation:
(e^x - 4)(e^x + 3) = 0
recall, that if any individual factor on the left side of the equation is equal to 0, the entire expression will be equal to 0.
e^x - 4 = 0
e^x + 3 = 0