阴影部分的面积
= (2X+X+Y+2X)(Y+X+Y+Y) - (X+Y)^2
= (5X+Y)(X+3Y) - (X+Y)^2
= 5X^2 + 16XY + 3Y^2 - X^2 - 2XY - Y^2
= 4X^2 + 14XY + 2Y^2
阴影部分的面积
= (2X+X+Y+2X)(Y+X+Y+Y) - (X+Y)^2
= (5X+Y)(X+3Y) - (X+Y)^2
= 5X^2 + 16XY + 3Y^2 - X^2 - 2XY - Y^2
= 4X^2 + 14XY + 2Y^2