you are right, thank you.

Mathematicas    Integrate[(x y (x^2 - y^2))/(3 (x^2 + y^2)^3), {x, 0, 2}, {y, 0, 1}] 

also gives 1/15

you are right, thank you.

Mathematicas    Integrate[(x y (x^2 - y^2))/(3 (x^2 + y^2)^3), {x, 0, 2}, {y, 0, 1}] 

also gives 1/15

Duh, thank you. This comes from using multipley CASs :)

Duh, thank you. This comes from using multipley CASs :)