Thanks for the help.... but
when I then integrate WRT y I get
2∫1 [5x^{2}y+(2/3) y^{3}] which I have to substitute in my limits of y=x and y=2x
but then this leaves me with a (2/3) (2x)^{3} term, which does not simplify well, and does not lead me to the correct answer.
Any ideas where I have gone wrong, thanks!
