已知数列{an}的各项均为正数,其前n项和为Sn,满足4Sn=an2+2an(n∈N*),设bn=(﹣1)n•anan+1,Tn为数列{bn}的前n项和,则T20=_____ .
更新时间:2020-05-19 07:41:41
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适中
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解题方法
【推荐1】设数列
的前
项和为
,若
,且
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b024dcba89b9bc12300583e25c1ed90.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/59acf223b79058dff78b70d75e1e644b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df63b9e77cc59d689ebb7caf2d3e19d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b024dcba89b9bc12300583e25c1ed90.png)
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解题方法
【推荐2】设数列
的前
项和为
,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3ed16bc1ac15e077c44956797fa3de1.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/ec6c104370c988cd818839b21f32829a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3ed16bc1ac15e077c44956797fa3de1.png)
您最近一年使用:0次
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(0.65)
【推荐1】若数列
的各项均为正数,前
项和为
,且
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5651e370d1a2402eff7836f854490aa1.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/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4d9920b4203a3f170a5e5403322269d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5651e370d1a2402eff7836f854490aa1.png)
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适中
(0.65)
解题方法
【推荐2】已知
是各项均为正数的无穷数列,其前
项和为
,且
给出下列四个结论:
①
;
②
各项中的最大值为2;
③
,使得
;
④
,都有
.
其中所有正确结论的序号是_______ .
![](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/3305664338775d189e720e2921485f5c.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d443f992059ac2ff73f2e3da3cbc5a3.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64a5c77806a86c309544871bf4985872.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71ca5ff810fe25d2945bc1d0529dd312.png)
④
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f8365233f341451598eb50525a1557a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe77f23003472aaf1a8b9220f71fe0bf.png)
其中所有正确结论的序号是
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