Proving the reduction formula, in need of help

Hello there people.

I have confronted a problem that I don't know how to do.

It is has follows:

Prove the reduction formula http://i.imgur.com/BEt3U.png

It would really helpful if someone were to help me understand this and show me how to prove it.

Thank you in advance to whoever that can :)

Re: Proving the reduction formula, in need of help

Re: Proving the reduction formula, in need of help

Well it's proving that the left side actually equals to the right side.

Re: Proving the reduction formula, in need of help

You have to integrate by parts. . , .