设数列
的前
项和为
,且
,
,则![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/3585f86a40f240c8a737acf2f66fc151.png?resizew=33)
_______ .
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/ee767bc208344004a75f4d0d0216ab98.png?resizew=32)
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/fcd0c52bde5f444aa34b1d0a7afa78ef.png?resizew=13)
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/7af5c2f604ce42c4b24682814d6a721d.png?resizew=19)
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/74fe6b5a20b74ae1bfda2366d3ef8f9b.png?resizew=39)
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/86f63814ddf74484a87c9d18d47b37b4.png?resizew=89)
![](https://img.xkw.com/dksih/QBM/2016/12/23/1619431100727296/1619431101112320/STEM/3585f86a40f240c8a737acf2f66fc151.png?resizew=33)
更新时间:2017-02-08 10:03:55
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【知识点】 前n项和与通项关系
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填空题-单空题
|
较易
(0.85)
解题方法
【推荐1】公比为2的等比数列的前
项和为
,若
,则
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