问题 解答题

(x+y)(x-y)+(x-y)2-(6x2y-2xy2)÷2y.

答案

原式=x2-y2+(x2-2xy+y2)-(3x2-xy)

=x2-y2+x2-2xy+y2-3x2+xy

=-x2-xy.

单项选择题
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