# Tricky integral

1. Apr 9, 2016

### squenshl

1. The problem statement, all variables and given/known data
How do I calculate $\int_a^b x\left(\frac{b-x}{b-a}\right)^{n-1} \; dx$???

2. Relevant equations

3. The attempt at a solution
I tried the substitution $u = \frac{b-x}{b-a}$ to no avail. Someone please help.

2. Apr 9, 2016

### Samy_A

That substitution should work: show us what went wrong when you tried it.
A little hint: don't bother with the $b-a$ in the denominator, as that is a constant. Set $u=b-x$.
EDIT: it doesn't really matter, both substitutions work just fine.

Last edited: Apr 9, 2016
3. Apr 9, 2016

### squenshl

Thanks a lot. I got it.