# Dealing with functions of several variables

1. Jun 29, 2008

### Nick89

1. The problem statement, all variables and given/known data
Assuming $x > -1$ and $y > -1$, find the following integral:
$$\displaystyle \int_0^1 \frac{t^x - t^y}{\ln t} dt$$

2. Relevant equations

3. The attempt at a solution
I have no idea where to start on this one... It came up in an exam for a class dealing with functions of several variables (eg, f(x,y,z)) so I don't think it's a usual substitution problem...

I tried writing it as $$\int t^x \ln(-t) dt$$ (minus the same for y) but I couldn't get any further...

Do I perhaps have to find some taylor polynomial or something?

2. Jun 29, 2008

### dirk_mec1

Re: Integral

This is wrong that's not the same integral ( do you know why?)

Use IBP.

3. Jun 29, 2008

### Nick89

Re: Integral

Sorry I screwed up there, heh.

Anyway, I just found out that this question in the exam was part of some chapter that is now omitted, that would explain why I have no idea how to start on this one ^^