记数列
的前
项和为
,若
,
,则
___ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29518f13a1ebc3fff8181c2d7cfba22f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01d8380672f31a02264b8a2233a9ee26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b708c8dcb2d66eb2ce0b3718a9cd924a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8b5ed9788d78a733c2fd237af8e931f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6812132ed21792ae9227bc473a143b43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01ad378a6e40157d3e6069c9ccdaa898.png)
更新时间:2018-03-10 17:01:51
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【推荐1】定义“等积数列”,在一个数列中,如果每一项与它后一项的积都为同一个常数,那么这个数列叫做等积数列,这个常数叫做该数列的公积.已知数列
是等积数列且
,公积为10,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c612fb2fed7c255a981cff9013063f4f.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/039e4fe671d61e59b96ee525c9df43e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c612fb2fed7c255a981cff9013063f4f.png)
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【推荐2】“开心辞典”中有这样的问题:给出一组数,要你根据规律填出后面的第几个数,现给出一组数:
它的第8个数是________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/099d56a4b4563a5f25636d8575e04a91.png)
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解题方法
【推荐1】已知数列
的前
项和
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d36243198e5e20c56399e4ad5ac3c519.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a26aa4cbbc507eb4743d9c52a94f9e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d36243198e5e20c56399e4ad5ac3c519.png)
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【推荐2】在数列
中,若前n项和
满足
,则该数列的通项公式![](https://img.xkw.com/dksih/QBM/2010/11/10/1569895579484160/1569895584899072/STEM/86f88ae73a4d4ac1b13d8e5732f01d05.png?resizew=37)
_________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/498b4cc9b90f15a7fc5a1a1f46ddaa39.png)
![](https://img.xkw.com/dksih/QBM/2010/11/10/1569895579484160/1569895584899072/STEM/86f88ae73a4d4ac1b13d8e5732f01d05.png?resizew=37)
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