已知数列
的前n项和为
,若
,
,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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e8c65f76456f36c80e28d926ca03b49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d36243198e5e20c56399e4ad5ac3c519.png)
更新时间:2022-10-30 14:52:52
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相似题推荐
填空题-单空题
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适中
(0.65)
【推荐1】已知
是公比为
的等比数列
的前
项和.若对任意的
,都有
成立,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad0d99fef1aa4dbcc6dc7b30b7d2c9a9.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/694b52596fdfcc391b23b3894ad85ec6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e069c80482ca550969858cc4a4010e66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad0d99fef1aa4dbcc6dc7b30b7d2c9a9.png)
您最近一年使用:0次
填空题-单空题
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适中
(0.65)
【推荐2】为了解某次测验成绩,在全年级随机地抽查了100名学生的成绩,得到频率分布直方图(如图),由于某种原因使部分数据丢失,但知道后5组的学生人数成等比数列,设90分以下人数为38,最大频率为b,则b的值为__ .
![](https://img.xkw.com/dksih/QBM/2021/6/7/2738081493401600/2826422334267392/STEM/60e3d940b6f64c569cc93a29a4851986.png?resizew=436)
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填空题-双空题
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适中
(0.65)
解题方法
【推荐1】设
为数列
的前
项和,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfc875ca919921e8f63a6fca648561b.png)
______ ;![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ceee1fc81f039e5592c0ad8c4208ed4.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61edbb55a806ba1e1a7c1889f0454b7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfc875ca919921e8f63a6fca648561b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ceee1fc81f039e5592c0ad8c4208ed4.png)
您最近一年使用:0次
填空题-单空题
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适中
(0.65)
解题方法
【推荐2】记
为数列
的前n项和,已知
是公差为
的等差数列.若
恒成立,则
的最小值为_________________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccbfd3118462f6044e9a67d16fbbac3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0488a565567fbbd35208ed7dc833f2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
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