Hi!

I remember at school there used to be this formula that we blindly used as a tool whenever something like this popped up, then we learnt that it's in fact a form substitution method:

.

⌠

⌡ u'(x) . u^n(x) dx =

⌠

⌡ u^n du

Can you know why? Just remeber that

u' = du/dx.

And remeber, by this so called

*change of variable method* we're now integrating w.r.t.

and not

. So if

and the limits are

x = 0, 1, the limits of

are

1, 3.

That plus TKHunny's hint, can you complete this?

Editing Note: Sorry, there's a problem with the LaTeX compiler