Yes, your substitution is correct.
I have the double integral of....
the inner integral goes from 0 to 1
the outer integral goes from 0 to 2
Do we need to u-sub for this, because I can't see what we need to look for if that's the case.
if it IS u-sub, this is what I may have:
u = x^2
du = 2xdx
xdx = (1/2)du