已知数列
的前n项和为
,则
的值为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b15d62fd603fa352f1028a3c59a548fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a48e81b54f78b96294295542b010dfb.png)
更新时间:2022-03-18 15:50:28
|
相似题推荐
填空题-单空题
|
适中
(0.65)
解题方法
【推荐1】已知数列
的前
项和为
,且
,
,则下列结论:①数列
是等比数列;②当
时,
;③当
时,
;④
.其中正确的有_____________ .(填序号)
![](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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/613915e81a8eaf5363040516a6e27cfe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a1a2208a768892a3db2e86abdae1164.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/194b8ab194c7d299d5c3e0f09ec18384.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/559fcc82e813f5d6c6d56675e0f360be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f970f380a12c843bb4a74ff34a15b2ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ae24081e1d9dd8753d1356e17101831.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c04bdf41109eee4f1921e5d1ad3b734f.png)
您最近一年使用:0次
填空题-单空题
|
适中
(0.65)
【推荐2】已知数列
的各项均为正数,其前
项和为
,
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c2864e2ec3416cc4c081ac1f71a0af.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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2693734765399876e9e93cdb110231c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb87366c493cf449e7776b7455883f08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c2864e2ec3416cc4c081ac1f71a0af.png)
您最近一年使用:0次
【推荐1】已知数列
满足
,在
和
之间插入
个1,构成数列
,则数列
的前20项的和为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e4b5779873cb3f4366dbfdb983dec81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/090426eb29836bc30c006b3739c08057.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/448c909167b20a65638f8e141b3262cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
您最近一年使用:0次
【推荐2】已知如图的一个数阵,该阵第
行所有数的和记作
,
,数列
的前
项和记作
,则下列说法正确的是__________ .
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/23/29c11624-b193-42c2-81f8-08a5db4cad3d.png?resizew=192)
①![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4f71b16f5f4d89968dc9118696f82d.png)
②![](https://staticzujuan.xkw.com/quesimg/Upload/formula/885ce7acc4bd772f720c79661a49325a.png)
③![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df427ddc416f6c1e7b3a1c6ce91b3c99.png)
④
![](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/d84639aa6c02d5a5d5b4e4f0d833011c.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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/23/29c11624-b193-42c2-81f8-08a5db4cad3d.png?resizew=192)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4f71b16f5f4d89968dc9118696f82d.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/885ce7acc4bd772f720c79661a49325a.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df427ddc416f6c1e7b3a1c6ce91b3c99.png)
④
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b8c2eb0c42fce6a49924e88f7a90b29.png)
您最近一年使用:0次