已知各项均为正数的等比数列
的前
项和为
,若
,且
与
的等差中项为
,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/5678e0ec5f45bd0a1780f390fed1d8bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daf464629fa321a6ff7401ab79f07083.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da4cd81500bdb43118150dbdb1541e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d59ab85c075a09d55d69e159e4abb268.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9620357ea5be4037cfdccd09a27d3862.png)
A.15 | B.30 | C.36 | D.78 |
更新时间:2024-05-07 13:04:14
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【推荐1】已知等差数列
的前
项和为
,若
,
,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/fe98dae6e275a3b14a20ee5cabc77165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942ec06e504421dc2f9d6082046f80f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adf14ebc775db2414a5a960badca8960.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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【推荐2】在数列
中,
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fa82f592293e037bf9825024cd7e9d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5960b9315bdc7246c0510fe3d35c5c7.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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【推荐2】已知等比数列
中,
,
,则公比
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c439d75a2be60e630ce26ad243c1b6b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffc750403440663316cc8f42730026f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad0d99fef1aa4dbcc6dc7b30b7d2c9a9.png)
A.-2 | B.2 | C.3 | D.3或-3 |
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【推荐1】已知数列
的前n项和
满足
,(
),则
的取值范围是( )
![](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/c9bc04bdb4bad9dc2372075183092dd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28652e52c0b02a343e618935ea625cbf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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【推荐2】在等比数列
中,
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0d1a57aa572849f9d663c4305c1bd98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c2864e2ec3416cc4c081ac1f71a0af.png)
A.8 | B.15 | C.![]() | D.31 |
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【推荐3】在流行病学中,基本传染数
是指在没有外力介入,同时所有人都没有免疫力的情况下,一个感染者平均传染的人数.初始感染者传染
个人,为第一轮传染,这
个人中每人再传染
个人,为第二轮传染,…….
一般由疾病的感染周期、感染者与其他人的接触频率、每次接触过程中传染的概率决定.注射新冠疫苗后可以使身体对新冠病毒产生抗体,但是正常情况下不能提高人体免疫力,据统计最新一轮的奥密克戎新冠变异株的基本传染数
,感染周期为4天,设从一位感染者开始,传播若干轮后感染的总人数超过7200人,需要的天数至少为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a4ea45063e04c5e5c0ebb7b556c642.png)
A.4 | B.12 | C.16 | D.20 |
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