1 . 若等差数列
的首项
,
,记
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d17f3bfd1e8c6d6284efdb69bcbada97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73d774634e468a66a09297481b477cf0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c3c2263e48afd4f7b961a1ed4539222.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
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2024-01-09更新
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701次组卷
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3卷引用:天津市武清区河西务中学2023-2024学年高二上学期第三次统练数学试卷
天津市武清区河西务中学2023-2024学年高二上学期第三次统练数学试卷广东省惠州市第一中学2024届高三上学期第四次阶段测试数学试题(已下线)1.2.2等差数列的前n项和公式(分层练习)-2023-2024学年高二数学同步精品课堂(北师大版2019选择性必修第二册)
解题方法
2 . 记
为等差数列
的前n项和,已知
,
,
,
的前n项和为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ac577f987d768e1a115f2747ec0fd6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3977c8261a26b09c1aa8d1ff87075666.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9ebf05ca12f9da810b2b10e066ececf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
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