I´m not sure how to integrate this, should I do a change of variables (we haven't seen it yet in our course)? Is there any other way?
$$ \int_0^2\int_0^1 (x+y)^8 dx dy $$
I'm rather interested in the general case, but this is the integral that motivated the question.
EDIT: I know expanding this using the binomial theorem works. However I don't think this is the intent of the exercise. As I said, I want to know about some technique to use in more general cases.