do u know how to calculate this integral?

Dear all,

Do u know how to calculate this integral: integral (from 0 to 1) of
(x^k*(1-x)^(n-k)dx?

1-|
| x^k * (1-x)^(n-k) dx
|- 0

I know the result is (n-k)!k!/(n+1)!, but get difficulty to derive it
to the result.

Thanks

.