I = ∫<0, π/2>dx∫<0, 2>xycos(xy^2)dy= (1/2)∫<0, π/2>dx∫<0, 2>cos(xy^2)d(xy^2)= (1/2)∫<0, π/2>dx[sin(xy^2)]<0, 2>= (1/2)∫<0, π/2>sin4xdx = -(1/8)[cos4x]<0, π/2> = 1/8
