问题 解答题
化简求值(x+y)(x-y)+(x-y)2-(6x2y-2xy2)÷(2y),其中x=-2,y=
1
3
答案

(x+y)(x-y)+(x-y)2-(6x2y-2xy2)÷(2y),

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

=-x2-xy,

当x=-2,y=

1
3
时,

原式=-(-2)2-(-2)×

1
3
=-4+
2
3
=-
10
3

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