20-21高二·全国·课后作业
解题方法
1 . 设
是等比数列,且
,证明数列
是等差数列,并求出这个等差数列的首项与公差.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9645bd4d2002993b90ec6d48f9c04f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4711944aa361bd9f2ed566b24c6888ec.png)
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20-21高二·全国·课后作业
2 . (1)求等差数列2,5,8,…的第4项与第10项;
(2)求等差数列12,7,2,…的第15项.
(2)求等差数列12,7,2,…的第15项.
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20-21高二·全国·课后作业
3 . 如果
是等差数列,而且正整数
,
,
,
满足
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fb679318d0c9819b82e51a1750b502a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/095397b70a73758437ba2198b61fd79b.png)
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20-21高二·全国·课后作业
4 . 已知等差数列
的首项为17,公差为
,则此等差数列从第几项开始出现负数?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7df4ff609899eb9d5887a236f65b748c.png)
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20-21高二·全国·课后作业
5 . 在等差数列
中:
(1)已知
,求首项
与公差d;
(2)已知
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56c69c89f9a4bf3d75e129dbb0b6880c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/024af739e2a9b1c16ebbb8afc6c79817.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5bbae9353140c2235610852d04a9a3f.png)
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2021-11-04更新
|
471次组卷
|
3卷引用:第五章 数列 5.2 等差数列 5.2.1 等差数列
20-21高二·全国·课后作业
6 . 已知安装在一个公共轴上的5个皮带轮的直径成等差数列,其中最大的与最小的皮带轮的直径分别为
与
,求中间3个皮带轮的直径.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66e66d5ff831e837398b871441f9479e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c077e21affbe7f9f8bb6d1f57b7e6c59.png)
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20-21高二·全国·课后作业
7 . 在等差数列
中:
(1)已知
,
,求
;
(2)已知
,
,求
;
(3)已知
,
,求
及
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ecf69901899bba130968c7a091790d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f2572192cc7ca046e9a3155ef3e56a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7da2f386b78cdf6489efaa2f5820d3e.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b47268b6b6be4d9618757ab606023768.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc807ea4b8a7ed325aee49aa292552ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b2b5232a2319db7fa5d18baf85e3dd6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ccc1de760f2f22c064ebf9b0e3c5bd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fd71bc7e6668f90f259ad0b06dd60c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
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20-21高二·全国·课后作业
解题方法
8 . 已知等差数列
的前n项和为
,若
,求
.
![](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/122d7d0ef6ce3e0e6a816c8987bb74b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/711161d23bed5161de370857a687c3ea.png)
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20-21高二·全国·课后作业
9 . 求等差数列63,60,57,…,
的各项的和.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95e35f76e01c3979ae5987f7729f9856.png)
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20-21高二·全国·课后作业
解题方法
10 . 已知等差数列
中,
,求这个数列前8项的和.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4584a3a62f35f89ef2c8ae7880b73f1.png)
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