若等差数列
的首项
,
,记
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7978d7bd6f6caf9ac9837ffce5f89654.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a1404c7e8a894900a5265a502adf478.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73d774634e468a66a09297481b477cf0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/479ca2b29acd24bc273a1d6859339f1e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7978d7bd6f6caf9ac9837ffce5f89654.png)
23-24高二上·江苏苏州·阶段练习 查看更多[4]
江苏省苏州市吴江中学2023-2024学年高二上学期10月月考数学试题(已下线)4.2 等差数列(5)(已下线)第03讲 4.2.2等差数列的前 项和公式(2)河南省焦作市第十二中学2023-2024学年高二上学期12月月考数学试题
更新时间:2023-10-16 19:23:13
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【推荐1】记数列
的前
项和为
,若
,且
是等比数列
的前三项,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88fa0877ffbcd7a4a631bfd0424b9ad2.png)
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【推荐2】在2015年苏州世兵赛期间,某景点用乒乓球堆成若干堆“正三棱锥”形的装饰品,其中第1堆只有1层,就一个球;第2,3,4,……堆最底层(第一层)分别按图中所示方式固定摆放,从第二层开始,每层的小球自然垒放在下一层之上,第n堆第n层就放一个乒乓球.记第n堆的乒乓球总数为
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__________ ,
=__________ .
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【推荐1】已知数列
的前
项和
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
__________ ,
的前
项和![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7978d7bd6f6caf9ac9837ffce5f89654.png)
__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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【推荐2】已知
是数列
的前
项和,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
________ ;若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f6d2f9704c53877827f4bb0e3bb6844.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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