# Homework Help: Evaluate the Integral

1. Oct 4, 2013

### IamBatman

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

Hi guys, so I've been having some trouble with this specific integral, and would like some help on how to solve it.

$\int^1_0\sqrt{1+e^{-x}}/e^x$.

2. The attempt at a solution

Editing

Next stage I'm sort of confused because I've never encountered two variables with "u".

Last edited: Oct 4, 2013
2. Oct 4, 2013

### SteamKing

Staff Emeritus
With you u substitution, all you have done is replace 'x' with 'u'. You haven't done any essential simplification to the integrand.

I would suggest looking at integration by parts. If you can find candidates for u and v with parts, then further substitution might be warranted.

3. Oct 4, 2013

### IamBatman

Yeah I wasn't sure if I should substitute more lol or just go through with algebra. Thanks.

4. Oct 4, 2013

### freshman2013

Actually usub does work. Re write e^x in the denominator as e^-x times the squareroot expression. u=e^-x+1. does it looks like du could be written in terms of e^-x?

5. Oct 4, 2013

### IamBatman

I figured it out

IT HAS BEEN SOLVED :)!

6. Oct 4, 2013

I am Batman.