Question

Integrate:

Answer 1

\[\int\limits_{-\infty}^{+\infty} \frac{ dx }{ e ^{x} + e ^{-x} }\]

Answer 2

using u-sub\[u=e^x\]

Answer 3

how will you be able to find du? I mean substitute for du. we need du to integrate...

Answer 4

well\[du=e^x dx=u \ dx\]\[dx=\frac{du}{u}\]right? :)

Answer 5

oh.. ^_^