若数列{an}的前n项之和为Sn,且满足lg (Sn+1)=n,求证:数列{an}是等比数列.
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若数列{an}的前n项之和为Sn,且满足lg (Sn+1)=n,求证:数列{an}是等比数列.
![若数列{an}的前n项之和为Sn,且满足lg (Sn+1)=n,求证:数列{an}是等比数列.](/uploads/image/z/17853603-51-3.jpg?t=%E8%8B%A5%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E4%B9%8B%E5%92%8C%E4%B8%BASn%EF%BC%8C%E4%B8%94%E6%BB%A1%E8%B6%B3lg%26nbsp%3B%EF%BC%88Sn%2B1%EF%BC%89%3Dn%EF%BC%8C%E6%B1%82%E8%AF%81%EF%BC%9A%E6%95%B0%E5%88%97%7Ban%7D%E6%98%AF%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%EF%BC%8E)
∵lg (Sn+1)=n,
∴sn+1=10n,
∴sn=10n-1,
∴数列前n项和满足等比数列的公式,
∴数列是等比数列.
∴sn+1=10n,
∴sn=10n-1,
∴数列前n项和满足等比数列的公式,
∴数列是等比数列.
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