In this problem I have drawn out the region specified and noticed two sets of parallel lines indicating to me that a change of variable(u and v) are able to be used to solve this integral.
I decided that u=y-x and v = -2x-y then solving for x and y I obtain x= (u-v)/3 and y = (4u-v)/3
From here I can compute the jacobian but I want to be sure the work above is correct before I move on. Can anyone please confirm?
For this second problem can anyone verify that it has been completed correctly
I think I have the right absolute minimum and maximum. Can someone also verify ?