# Integral problem

1. Apr 25, 2010

### cragar

1. The problem statement, all variables and given/known data
integrate 1/((e^(x-1)+1))
and (x)/((e^(x-1)+1))

3. The attempt at a solution
i tried using integration parts , and partial fractions but i am not really sure what to do
any help will be much appreciated .

2. Apr 25, 2010

### gabbagabbahey

I'd start by multiplying both numerator and denominator by $e$...after that, just use the following trick:

$$\frac{e}{e^x+e}=\frac{e+e^x-e^x}{e^x+e}=1-\frac{e^x}{e^x+e}$$

3. Apr 25, 2010

### cragar

thanks for you help , that is a really slick trick