1. In each case, calculate JR J f(x, y)dA. (a) f(x, y) = x2 - 2xy, R is the rectangle [-1, 2] x [2, 4] (b) f(x, y) = rey , R is the region bounded by y = 2, y = 4, and the y axis. (c) f(x, y) = ysin(x), R is the triangle with vertices at (0, 0), (1, 0), and (1, 4). (d) f(x, y) = x3y, R is the region bounded by y = x2 - 1 and y = -x + 1. (e) f(x, y) = vx2 + y2, R is the region inside the cardioid r = 4(1 - sin(0))