设等差数列
的前
项和为
,若
,则
=_______ .
![](https://img.xkw.com/dksih/QBM/2016/6/21/1572754529492992/1572754535735296/STEM/2b8447320ea742c09235024baa548059.png?resizew=31)
![](https://img.xkw.com/dksih/QBM/2016/6/21/1572754529492992/1572754535735296/STEM/1d6aba7c30ca4303a7145b9082c165b6.png?resizew=13)
![](https://img.xkw.com/dksih/QBM/2016/6/21/1572754529492992/1572754535735296/STEM/1b5b70d9fbb24381b6649581cd10aad7.png?resizew=20)
![](https://img.xkw.com/dksih/QBM/2016/6/21/1572754529492992/1572754535735296/STEM/b5499b1621c848b0a801417eced52da1.png?resizew=156)
![](https://img.xkw.com/dksih/QBM/2016/6/21/1572754529492992/1572754535735296/STEM/c44e16cf44bf4f6db841c85b205d97fb.png?resizew=23)
更新时间:2016-12-04 11:20:12
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【推荐1】等差数列
满足
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/442f97df82c935264dd59ad7909af906.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c18117945064e8ad3dbbd8fdcb941b3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b38fda654c021e994ac899d0ecdc6955.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/442f97df82c935264dd59ad7909af906.png)
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【推荐2】已知数列
为等比数列,其前
项和为
,且公比
;数列
为等差数列,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e9c3d80ac6c1a579eececfca16f0a55.png)
__________
.(填写“
”,“
”或“
”)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2b429d189e2b9fe22e55e82d0f831a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/761f70e0d9cc81e15654790a10b1767a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e9c3d80ac6c1a579eececfca16f0a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20d98be54935b736c6c917feb9c5913e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392cdb9d30684cce244bef94b8d861b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ff7942da6c3fc4005256fb1458557c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
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【推荐1】方程
的最小的20个正实数解之和为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87a34009b48fec4b1bc4a5291274e949.png)
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【推荐2】我国南宋数学家杨辉在他所著的《详解九章算法》中提出了如图所示的三角形数表,这就是著名的“杨辉三角”,它是二项式系数在三角形中的一种几何排列.从第1行开始,第
行从左至右的数字之和记为
,如:
为各项非零的等差数列,其前
项和为
,且
,则数列
的前
项和![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7978d7bd6f6caf9ac9837ffce5f89654.png)
________________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c80874cb6923e471aadeba2c2b0c41f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/129e15fb4c11132471174c6a3c359555.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9a6c852d593cb9f6bdfd9eeddb50fa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7978d7bd6f6caf9ac9837ffce5f89654.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/23/ec57743a-c925-484b-ae6e-88bb4bc08149.png?resizew=208)
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