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数学救济1要有步骤

2008-03-15 19:36:29不***
要有步骤数学救济1要有步骤:分解因式:(n+1)an^2+ +1 -nan+1^2=0 [nan+1-(n+1)an].(an+an+1)=0 ?

最佳回答

  • 分解因式:(n+1)an^2+ +1 -nan+1^2=0 [nan+1-(n+1)an].(an+an+1)=0 因为任意的an>0,所以上式中只有nan+1-(n+1)an=0 即:an+1/an=n+1/n a1=2*1 a2=2*2 ............. an=2*n an+1=2*(n+1) ............. an=2n Sn=n*(n+1)
    2008-03-15 22:04:02
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