# Homework Help: Integral of 2/((e^(-x))+1)

1. May 25, 2009

### bigdummy3000

1. The problem statement, all variables and given/known data

integral of 2/((e^(-x))+1)

2. Relevant equations

how do you do this?

3. The attempt at a solution

no freaking clue! this is the BS i came up with

2(x-ln(e^-x + 1) + C)

2. May 25, 2009

### Dunkle

You can rewrite the integrand and then use a simple substitution. Hint: multiply the numerator and denominator by e^x and then simplify.

Last edited: May 25, 2009
3. May 25, 2009

### bigdummy3000

so then...i want to find the integral of e^x/(e^x + 1)...and i think i want to use substitution? u = e^x + 1. but then i do something wrong somewhere...i'm getting retarded answers...

4. May 25, 2009

### Cyosis

If $u=e^x+1$ then du=?