Question

Integral e^x/(1+e^2x) dx

Answer 1

:)

Answer 2

arctg(e^x) +C

Answer 3

does its integral is defined?

Answer 4

Integral value = arctg(e^x) +C

Answer 5

simple substitution
e^x = t

Answer 6

\[\int\limits dt/1+t ^{2} = arctg (t) +C\]