Hi again,

Im studying for a exam tomorrow and have another question for this forum =)

⌠

⌡ e^(-x) sec^2(e^(-x)) dx

For this problem I approached it by substituting sec^2(e^(-x)) w/ u^2 => I then got stuck w/ (sec^3(e^(-x))/3 * 1/(sec(e^(-x))*tan(e^(-x))) + C

The answer key just gives -tan(e(-x)) + C

Please help