先化简,再求值:x+根号xy/根号xy+y+根号xy-y/x-xy,其中x=根号3+1,y=根号3-1

问题描述:

先化简,再求值:x+根号xy/根号xy+y+根号xy-y/x-xy,其中x=根号3+1,y=根号3-1
1个回答 分类:数学 2014-10-04

问题解答:

我来补答
[x+√(xy)]/[√(xy)+y]+[√(xy)-y]/[x-√(xy)]
=[x+√(xy)]*[√(xy)-y]/(xy-y²)+[√(xy)-y]*[x+√(xy)]/(x²-xy)
=[x√(xy)-y√(xy)]/[y(x-y)]+[x√(xy)-y√(xy)]/[x(x-y)]
=√(xy)/y+√(xy)/x
=√(xy)(x+y)/xy
=√[(√3+1)(√3-1)](√3+1+√3-1)/[(√3+1)(√3-1)]
=√2*2√3/2=√6
对吗.
 
 
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