如图数表,它的第一行数由正整数从小到大排列得到,此后下一行数由前一行每两个相邻的数的和写在这两个数正中间下方得到.依次类推,则该数表中,第n行第1个数是____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b47ff866f4b39a9ccb78cc4347390b9d.png)
21-22高二下·内蒙古赤峰·阶段练习 查看更多[2]
更新时间:2022-06-10 16:21:04
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解题方法
【推荐1】数列
的项是由1或2构成,且首项为1,在第
个1和第
个1之间有
个2,即数列
为:1,2,1,2,2,2,1,2,2,2,2,2,1,…,记数列
的前
项和为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dec6439c99c6a996a48b7d9e57c21208.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b00f4eb7f1bd2ccefbabf0c1dfa8f69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/897d8f6cf00391f1b3ff70432f0121b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.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/dec6439c99c6a996a48b7d9e57c21208.png)
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【推荐2】如图所示的三角形数阵叫“莱布尼兹调和三角形”,它们是由整数的倒数组成的,第
行有
个数且两端的数均为
,每个数是它下一行左右相邻两数的和,如
,
,
,…,则第9行第4个数(从左往右数)为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93ebfac5684353acf9abcebb9d82d9f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48e793a209cbb7698b63ce86071061bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/660f41a92328772f61ade4e991d5ac0a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ebcc3f6b9a6e9b4dcd68382ba32a00b.png)
![](https://img.xkw.com/dksih/QBM/2020/5/4/2455622807781376/2455660853485568/STEM/4b7e52723919497397e668e9f349b506.png?resizew=176)
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【推荐1】记公差
不为0的等差数列
的前
项和为
,
,
成等比数列,则公差
=_________ ;数列
的前
项和为
=___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5170584604571b5e1afd5ece941e2e73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50d0e1bab477a701c7336210b538c9c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://img.xkw.com/dksih/QBM/2018/5/14/1945174583541760/2008677119377408/STEM/481afbe7aec44d07bf11f3727333ba41.png?resizew=19)
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【推荐2】数列
满足
,
,则
的通项公式为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0be6e7d3f1dcd8ecd4bd9389656e6b36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
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解题方法
【推荐1】已知等差数列
的前
项和为
,
,
,若
对任意
恒成立,则实数
的取值范围为__________ .
![](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/afbfd6b761451716ba3d7130c93497ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d2cd50f64663d8060269e12cd238d20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f093c61867ee4ce75f951d46b9b123.png)
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解题方法
【推荐2】已知等差数列
的前
项和为
,若
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bc625e19e7ca2b9d097f67a3d472e47.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/8c9b5080aa2e9c889aac8e378d83dfee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/459a75c79e2256f5b43f7eb3d609230a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bc625e19e7ca2b9d097f67a3d472e47.png)
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