已知xy=2,x-y=3,求(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)/2y的值.
题目
已知xy=2,x-y=3,求(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)/2y的值.
答案
(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)÷2y =(x+y)(x-y)-y^2+(x-y)^2-2y(3x^2-xy)÷2y =(x+y)(x-y)-y^2+(x-y)^2-(3x^2-xy) =(x+y)(x-y)+(x-y)^2-y^2-(3x^2-xy) =[(x+y)+(x-y)](x-y)-y^2-(3x^2-x...
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