I'm talking about this integral, it seems like you re talking about integral from the main postThank you guys, I got it now, was so easy but I'm blind sometimes...
What about next integral, integration area is so weird...
[math]\iint_D(x+y)dxdy,\,\,D:\,\,x\geq0,\,\,y\geq0,\,\,\sqrt{x}+\sqrt{y}\leq1[/math]