# Extremely hard integral - pls help

1. Oct 28, 2012

### Nikitin

1. The problem statement, all variables and given/known data
integrate the following function: x*√(2x-x2)

2. Relevant equations
substitutions?

3. The attempt at a solution
I substituted x with x=2sin2u. From that I ended up with ∫x*√(2x-x2)= 16∫sin4u*cos2u

Now I'm supposed to use a formula from an integrals table.. but which?

2. Oct 28, 2012

### dextercioby

You should complete the square under the sqrt. $\displaystyle{\sqrt{1-(1-x)^2}}$ and then make the natural substitution.

3. Oct 28, 2012

### Nikitin

edit: nvm

Last edited: Oct 28, 2012