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方程解的和

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longzaifei posted 2014-10-9 22:08 |Read mode
求方程$\dfrac{1}{x^2-1}+\dfrac{2}{x^2-2}+\dfrac{3}{x^2-3}+\dfrac{4}{x^2-4}=2010x-4 $的所有解之和。

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战巡 posted 2014-10-10 01:18
回复 1# longzaifei


求和只要看最高次的两项系数就够了,其他的统统不用管
左边下面通分后为8次,分母7次,与右边通分后分子才会出现8次和9次,显然化简后最高次的两项只能出现在左边分母的8次项和这两个相乘,又显然分母8次项系数为1,也就是分子8次项系数为$-4$,9次项系数$2010$,和也就是$\frac{4}{2010}$

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original poster longzaifei posted 2014-10-10 09:15
回复 2# 战巡
谢谢!!

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wzxsjz posted 2014-10-11 13:27
如果说实数解,就好玩了!

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