问题 计算题

计算:(﹣x﹣y)(x﹣y)+(x+y)2

答案

解:(﹣x﹣y)(x﹣y)+(x+y)2

=(﹣y)2﹣x2+(x+y)2

=﹣x2+y2+x2+2xy+y2

=2y2+2xy.

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