1 . 若5是a与b的等差中项,4是a与b的等比中项,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2b1b96f5050de3bc7ae53c7bf0c21e8.png)
__________ ;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2b1b96f5050de3bc7ae53c7bf0c21e8.png)
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2022-12-27更新
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682次组卷
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3卷引用:山东省莱西市第一中学2022-2023学年高二学业水平检测(二) 数学试题
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2 . 在等差数列
中,
,公差
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfc875ca919921e8f63a6fca648561b.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/c5c1344592c925b273f2cb9b9e47ebbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfc875ca919921e8f63a6fca648561b.png)
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2022-04-11更新
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1058次组卷
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4卷引用:贵州省2021-2022学年高二7月学业水平考试数学试题
解题方法
3 . 若数列
通项公式为
,记前n项和为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9bbe98100c8067ff36ac536d043a85.png)
___________ ;![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9620357ea5be4037cfdccd09a27d3862.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9260f8989cfd0ffca5a49ffbc0668f14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9bbe98100c8067ff36ac536d043a85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9620357ea5be4037cfdccd09a27d3862.png)
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4 . 在等差数列
中,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9bbe98100c8067ff36ac536d043a85.png)
_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c67bb9405b5d575f38602e4036ef6f87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9bbe98100c8067ff36ac536d043a85.png)
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5 . 已知
为等差数列
的前
项和,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5af1f1b7e9e20d799ee3c06b89a0611c.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/164afbf55ea7cd7d66158620616e604e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5af1f1b7e9e20d799ee3c06b89a0611c.png)
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2021-10-22更新
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645次组卷
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2卷引用:2023年浙江省普通高中学业水平考试押题预测数学试题
20-21高二上·全国·课后作业
6 . 在等差数列{an}中,a1>0,d=
,an=3,Sn=
,则a1=________ ,n=________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7163395f9aaa29be7f6b3106ba48b744.png)
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7 . 某公司购置了一台价值220元的设备,随着设备在使用过程中老化,其价值会逐年减少.经验表明,每经过一年其价值就会减少d(d为正常数)万元.已知这台设备的使用年限为10年,超过10年,它的价值将低于购进价值的5%,设备将报废,则d的取值范围为____ .
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2021-03-26更新
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2卷引用:江苏省南通市通州高级中学2020-2021学年高二上学期第一次学分认定考试数学试题
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8 . 已知等差数列{an}的公差d不为0,且
,
,
成等比数列,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e843f5c36547fe7e3225956667fb55e.png)
____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f65fc200f10b97588a0c9896277c9c64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fd71bc7e6668f90f259ad0b06dd60c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e843f5c36547fe7e3225956667fb55e.png)
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解题方法
9 . 若等差数列
满足
,则
的前7项的和为________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb0abedd59476f8793d5a8948590a70c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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10 . 在等差数列
中,已知a3=6,a5=a2+9,则a6 = ________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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2021-03-04更新
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842次组卷
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3卷引用:广东省2021年普通高中学业水平考试数学试题