化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方

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化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x

化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方
化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方

化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方
(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方
=x²-2xy-3y²-x²+4y²-x²+2xy-y²
=(x²-x²-x²)+(2xy-2xy)+(4y²-3y²-y²)
=-x²