1 . 若等差数列
满足
则
的最大值为_____
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddd97dae9e9c0ea21db5646ef88999f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/364f2e680e15ca52f466c10dc90287c4.png)
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2020-05-06更新
|
800次组卷
|
4卷引用:上海市上海交通大学附属中学2019-2020学年高一下学期期中数学试题
解题方法
2 . 已知数列
的奇数项和偶数项为公比为
的等比数列,
,且
.则数列
的前
项和的最小值为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/535fd9605b90ac7f0fed6025be9f851f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/855ba970de183d21672127127fc1bc27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/662addba4f63bec99e0b44ca42302232.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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名校
3 . 已知数列
的各项为正数,其前
项和为
满足
,设
.
(1)求证:数列
是等差数列,并求
的通项公式;
(2)设数列
的前
项和为
,求
的最大值.
(3)设数列
的通项公式为
,问: 是否存在正整数t,使得
成等差数列?若存在,求出t和m的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe229b24e2d56ff6b491725ceae4ff2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b708c8dcb2d66eb2ce0b3718a9cd924a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94150e72f46eea14cdbf97cfdf727756.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da708c5cdc9c9e40abea274cfc7646bb.png)
(1)求证:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe229b24e2d56ff6b491725ceae4ff2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe229b24e2d56ff6b491725ceae4ff2f.png)
(2)设数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bee4464b3b4eb6e52ee02f095aae84f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb26cd1601fe7e76e1e2dc0b4909324a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb26cd1601fe7e76e1e2dc0b4909324a.png)
(3)设数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cca3ebd10a38201939a3694cc95186a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff2b55ff05234d20f0c9746716636499.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3db3be50a61c90c25c94ee3267671c67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b22893fa68b9fc17954ed5ea7055b486.png)
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