hmm, can i get a little more hint? if i do a u sub. of u = e[tex]^{-x}[/tex], how do i get rid of
e[tex]^{-2x}[/tex]? I have tried do a u sub. of u = [tex]\sqrt{1-e^{-2x}}[/tex], but i ended up getting the [tex]\int du/e^{-x}[/tex], which i dont know how to proceed after this. What am i doing wrong?