(3xy)平方/(-xy)+(x-2y)平方-(x+2y)(x-2y)=
问题描述:
(3xy)平方/(-xy)+(x-2y)平方-(x+2y)(x-2y)=
答
(3xy)平方/(-xy)+(x-2y)平方-(x+2y)(x-2y)
=-9xy+(x-2y)(x-2y-x-2y)
=-9xy+(x-2y)(-4y)
=-9xy-4xy+8y²
=8y²-13xy
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