i just found this and try to solve.. but then since i left all of these for many years, so i cant remember some of the ways..

i will keep thinking of this because i'm not able to solve it.. and this make me suffer..

∫ x / (1 + ex) dx

You can't solve this. This integral cannot be solved in terms of elementary functions. Specifically, you need the polylogarithm to solve this.

You can't solve this. This integral cannot be solved in terms of elementary functions. Specifically, you need the polylogarithm to solve this.

ohh... i see... thank you micromass...
but if you want to.. can you show how to solve this by using the polylogarithm? :)

ohh... i see... thank you micromass...
but if you want to.. can you show how to solve this by using the polylogarithm? :)

Do you have any background in complex analysis?

Do you have any background in complex analysis?

yess.. but not so deep.. just a basic of complex analysis..

this problem cannot be solved normally. you can use integration by parts

integration by parts is this: ∫ u dv = u.v - ∫ v du

HallsofIvy
Homework Helper
What do you mean by that? "Integration by parts" is a normal integration method. And won't work here. As micromass said, that cannot be integrated in terms of elementary functions.

ohh... i see... thank you micromass...
but if you want to.. can you show how to solve this by using the polylogarithm? :)

If you know the polylogarithm functions, then the formal result is :

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