## yuki 5 years ago Can some one help me evaluate the integral ?

1. Yuki

$\int\limits e^x/(1+e^{2x}) dx$

2. Yuki

I thought the answer should be arctan(e^x) +c but somehow the answer tells me that there is a 1/2 multiplied to it. I can't figure out where it got that from.

3. anonymous

$\int\limits \frac{e^x}{1+e^{2x}} dx$$= \int\limits \frac{e^x}{1+(e^x)^2} dx$ let u = e^x and solve, how come? I got arcTan(e^x) too

4. anonymous

1/2 can come from $u=e ^{2x}$