我只知道答案是 8

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我只知道答案是8我只知道答案是8我只知道答案是8你好:(x^3-xy^2)/(x+y)÷(x^2-2xy+y^2)/x-(2y+2)/(y-x)=x*(x+y)(x-y)/(x+y)÷(x-y)^2/

我只知道答案是 8

我只知道答案是 8

我只知道答案是 8
你好:

(x^3-xy^2)/(x+y)÷(x^2-2xy+y^2)/x-(2y+2)/(y-x)
=x*(x+y)(x-y)/(x+y)÷(x-y)^2/x+(2y+2)/(x-y)
=x(x-y)*x/(x-y)^2+(2y+2)/(x-y)
=x^2/(x-y)+(2y+2)/(x-y)
=(x^2+2y+2)/(x-y)
代入:x=2, y=1
=(2*2+2*1+2)/(2-1)
=8

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