# Thread: help evaluating an integral

1. ## help evaluating an integral

How would you solve this question?
Evaluate ∫∫ e* (y-x)/(y+x)dxdy over the region in the xy plane bounded by x + y = 4, x + y = 2, the x-axis and the y-axis.

How would you draw ?

2. Originally Posted by student123
How would you solve this question?
Evaluate ∫∫ e* (y-x)/(y+x)dxdy over the region in the xy plane bounded by x + y = 4, x + y = 2, the x-axis and the y-axis.

How would you draw ?
I suggest a change of variable: $u = y - x$ and $v = y + x$.

You get a nice region in the uv-plane and the integrations appear straightforward. Don't forget to include the Jacobian of the transformation.