运用平方差公差,完全平方公式计算计算：（x+y-2)(x+y+3）(2x+y-3)(2x-y+3)

（x+y-2)(x+y+3）
=[(x+y)-2][(x+y)+3]
=(x+y)^2+(3-2)(x+y)-6
=(x+y)^2+(x+y)-6
=x^2+2xy+y^2+x+y-6
(2x+y-3)(2x-y+3)
=[2x+(y-3)][2x-(y+3)]
=(2x)^2-(y+3)^2
=4x^2-y^2-6y-9