问题描述: 已知xy=-2,x-y=3,求(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)÷2y 1个回答 分类:数学 2014-10-27 问题解答: 我来补答 (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-xy) =2x(x-y)-y^2-(3x^2-xy) =2x^2-2xy-y^2-3x^2+xy =-x^2-xy-y^2=-(x^2+y^2+xy)=-(x^2-2xy+y^2+3xy)=-[(x-y)^2+3xy]=-[3^2+3*(-2)]=-(9-6)=-3 展开全文阅读