1 . 已知等差数列
,
,那么首项![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbf2a0670374b228486e20ec71c9b7e8.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b92d1de7c995debeabf3e59467d62bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbf2a0670374b228486e20ec71c9b7e8.png)
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2 . 《张邱建算经》有这样一个问题:宫廷将黄金按照等差依次赏赐给甲、乙、丙、丁、戊、己、庚、辛、壬、癸这十位官人,前面的三人甲、乙和丙先进来,共领到黄金四斤;后面的四人庚、辛、壬、癸也按照所应领到得黄金三斤;中间的三人丁、戊、己尚未到,也按照应分得黄金数量留给,则戊应领黄金斤数为
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
3 . 已知
,数列
为等差数列,公差
,
为数列
前
项和,若满足
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c98c59cd4749afdd21e73529fc84323.png)
_____ ;![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e64c50878350cd3bc2223faf988b66c.png)
_____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb13dfa5fd853f10326b6b71f9ae144f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4ce64685821c3e55c07f151996ca8c3.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/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27e595839a406c5937b52f652e6a818e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c98c59cd4749afdd21e73529fc84323.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e64c50878350cd3bc2223faf988b66c.png)
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解题方法
4 . 设等差数列
的前n项和为
,若
,则
的公差为______ .
![](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/204b56e1db2c84b40d505563e386af84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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5 . 某电影院中,从第2排开始,每一排的座位数比前一排多两个座位,第1排有18个座位,最后一排有36个座位,则该电影院共有座位_____ 个.
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2020高三·江苏·专题练习
6 . 在等差数列
中,若
,则
的前6项和
的值为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a865c3545727db4b6a68b01a9b2e7a91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a48e81b54f78b96294295542b010dfb.png)
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7 . 设
,
都是等差数列,其中
中首项为8,公差为3,
中首项为12,公差为4.问:数列
,
是否有公共项?若有,求出第一个公共项,并写出由所有公共项组成的数列的通项公式.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
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2019高二上·全国·专题练习
8 . 已知等差数列
的前
项和为
,若
,且
、
、
成等比数列,则
( )
![](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/5188a12fa11e5152519a91ab89b94ce9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e0414c0b6fda7fee5eb71976e09da80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7999465d0e871febde66296a0cbf058c.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2020高三·全国·专题练习
9 . 已知等差数列
的前n项和为
,且
,
,数列
的首项为3,且
,则
( )
![](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/d5ef35b21da4cd8130642539d8245f83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7af9d6941ab0cc5d87c8f20a19385034.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06ea92902980c21bc18f5c68f316f559.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33da2a751a63f8946c11234ed55dab2b.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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