Hey there I need some help with this problem
Let be the region 0 <(or equal to) y <(or equal to) x
0 <(or equal to) x <(or equal to) 1
double integral over D of (x+y) dxdy
by making the change of variables x=u+v, and y=u-v
Check your answers by evaluating the iterated integral directly by using an iterated integral.
Please explain each step you did, so I can understand how to do this problem thanks.