问题描述: 数学:先化简再求值(x²+xy-2y²/x²-2xy+y²)-(1-xy²)(1+xy²)-x²÷1/y^4,其中x=根号3+根号2y=根号3-根号2 1个回答 分类:数学 2014-10-03 问题解答: 我来补答 (x²+xy-2y²/x²-2xy+y²)-(1-xy²)(1+xy²)-x²÷1/y^4=【(x+2y)(x-y)/(x-y)² 】-(1-x² y^4)-x² y^4=(x+2y)/(x-y)-1+x² y^4-x² y^4=(x+2y)/(x-y)-1=【(x+2y)-(x-y)】/(x-y)=3y/(x-y)你只告诉了x,没告诉y,自己在对照题目,将x.y带入求出就行 展开全文阅读