Sketch the domain

(a) Let F be the map u = x + y, v = y − 2x from the xy-plane to the uv-plane, and let Φ be its inverse. Use Eq. (14) to compute Jac(Φ).

(b) Compute  dx dy using the Change of Variables Formula with the map Φ. Hint: It is not necessary to solve for Φ explicitly.

D = {(x,y): 1 x + y 4, -4 y - 2x 1}