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求助`````````一道先化简再求值的题

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若X^2+Y^2-4X-2Y+5=0,将代数式((根号X+根号Y)^2-4(根号XY))/(X-(根号XY))先化简再求


1楼2008-04-21 23:06回复
    帮帮忙,小弟现在好困啊````````````


    2楼2008-04-21 23:09
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      真的算不出来拉```````````````


      3楼2008-04-21 23:12
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        • 211.139.151.*
        分子=(根x-根y)^2,分母=根x(根x-根x),故原式=1-根(x/y).方程等价于(x-2)^2+(y-1)^2,故x=2,y=1.


        4楼2008-04-21 23:28
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          不懂


          5楼2008-04-22 06:35
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            不懂


            6楼2008-04-22 06:35
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              • 211.139.151.*
              ………


              7楼2008-04-22 06:41
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                谢谢啊```````````````我会了```````````````````


                8楼2008-04-22 06:47
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                  • 211.139.151.*
                  不用谢^·^


                  9楼2008-04-22 07:58
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