已知数列an,若a1=1,nan+1=(n+2)Sn,求证Sn/n为等比数列已知数列an,若a1=1,nan+1=(n+2)Sn,求证数列Sn/n为等比数列,并且求Sn

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已知数列an,若a1=1,nan+1=(n+2)Sn,求证Sn/n为等比数列已知数列an,若a1=1,nan+1=(n+2)Sn,求证数列Sn/n为等比数列,并且求Sn
已知数列an,若a1=1,nan+1=(n+2)Sn,求证Sn/n为等比数列
已知数列an,若a1=1,nan+1=(n+2)Sn,求证数列Sn/n为等比数列,并且求Sn

已知数列an,若a1=1,nan+1=(n+2)Sn,求证Sn/n为等比数列已知数列an,若a1=1,nan+1=(n+2)Sn,求证数列Sn/n为等比数列,并且求Sn
na(n+1)=(n+2)Sn
n(Sn+1-Sn)=(n+2)Sn
nSn+1=2(n+1)Sn
Sn+1/(n+1)=2Sn/n
所以{Sn/n}是2为公比的等比数列