已知数列
的前
项和
.求:
(1)求数列
的通项公式;
(2)求数列
的前n项和
;
(3)求
的最小值.
![](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/8d4558d082c4423ceacf45a1c4c663ac.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba57c83d526ac308d1461e80fcca9f36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf72fb8c3aca7185ed1d5fff2b57abbf.png)
更新时间:2018-04-01 18:32:19
|
相似题推荐
【推荐1】对于数列
,若从第二项起,每一项与它的前一项之差都大于或等于(小于或等于)同一个常数
,则
叫做类等差数列,
叫做类等差数列的首项,
叫做类等差数列的类公差.
(1)若类等差数列
满足
,请类比等差数列的通项公式,求出数列
的通项不等式(要写出证明过程);
(2)若数列
中,
,
.判断数列
是否为类等差数列,若是,请证明;若不是,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7936359df4c926b72b48c6fdae55f12d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
(1)若类等差数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30d140c40a0f4e3c98d71437828245a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
(2)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/14835bf3f00139ccec0694d0924db795.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddda8e6c1ea80647c96a6b89ee544e1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41cf1da18d91f7c98086553d157d1a87.png)
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【推荐2】已知数列
的前n项和为
,且关于x的方程
,
有两个相等的实数根.
(1)求
的通项公式;
(2)若
,数列
的前n项和为
,且
对任意的
恒成立,求实数
的最大值.
![](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/fc5f25f52d5a0975aa4e22d17dded67b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a37a59558292ad6b3d0978bfd7484990.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd1100b5831d9d61fdba9fea833cd9c.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/bb39d60a45793977cdef3238bc8246c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a37a59558292ad6b3d0978bfd7484990.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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【推荐1】若
和
分别表示数列
和数列
的前
项和,对任意正整数
,有
,
.
(1)求数列
的通项公式;
(2)
,
,求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7d0eb4705be32a2de19a6b7fed567b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73e4f01109154d625e020c92bf207ed7.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/449592daa9865e61f0f6824fbb84f05b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bcc4300a9dc4211bd4cf8e2bb90a3d4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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解题方法
【推荐2】已知正项数列
的前
项和为
,且
.
(1)证明:
是等差数列.
(2)求数列
的前
项和为
![](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/f9295f2addeeddbc3250bf55b7d215cd.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d586c959dbb9ff51a85d2a598d2c85c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
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解题方法
【推荐1】已知
的内角
,
,
的对应边分别为
,
,
,
,
.
(1)求
的值;
(2)求
的面积的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51f3879d3428b961a844dadde3fa3b2a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcdb7a488910743dc5c63afb394b87e2.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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【推荐2】(1)已知
,且
.求证:
,
中至少有一个小于2.
(2)已知
,
,
是互不相等的正数,且
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69ee6696dee035519e1ba7fb78269830.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f9e131cdd242d56b6dba05ab3363ef3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10fe4e9871c2acac03e9a3388fd2877e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a2b29b47d6c7753d5359883c105c68d.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81e59019989b7dc2fb59b037ef6e010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd24c686fbaaa68705d654b880481ffe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f8f4d3c03ce40729b1cfc52da58bdb.png)
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【推荐3】商品价格与商品需求量是经济学中的一种基本关系,某服装公司需对新上市的一款服装制定合理的价格,需要了解服装的单价x(单位:元)与月销量y(单位:件)和月利润z(单位:元)的影响,对试销10个月的价格
和月销售量
(
)数据作了初步处理,得到如图所示的散点图及一些统计量的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/2/f49b7d91-bdf8-4af0-a321-be5d29c5cd6e.png?resizew=212)
表中
.
(1)根据散点图判断,
与
哪一个适宜作为需求量y关于价格x的回归方程类型?(给出判断即可,不必说明理由)
(2)根据(1)的判断结果及表中数据,建立y关于x的回归方程;
(3)已知这批服装的成本为每件10元,根据(1)的结果回答下列问题;
(i)预测当服装价格
时,月销售量的预报值是多少?
(ii)当服装价格x为何值时,月利润的预报值最大?(参考数据
)
附:对于一组数据,其回归直线的斜率和截距的最小二乘估计分别为
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97ea8f47d8d8d9e1832d52b1c7425450.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4de122ae929b1acaff321dec137622ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f70e0635d74c877367a9d586e462ef35.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/2/f49b7d91-bdf8-4af0-a321-be5d29c5cd6e.png?resizew=212)
x | ![]() | y | ![]() | ![]() | ![]() | ![]() |
61 | 0.018 | 372 | ![]() | 2670 | 26 | 0.0004 |
表中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f06ab6da6f3feae405774ccf19b91874.png)
(1)根据散点图判断,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6a5b1c19e4c57f1d259f8269e551c64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5a323be03360218b752b2fad5f22638.png)
(2)根据(1)的判断结果及表中数据,建立y关于x的回归方程;
(3)已知这批服装的成本为每件10元,根据(1)的结果回答下列问题;
(i)预测当服装价格
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04df7cdab2a938e8c64b302b32e8d490.png)
(ii)当服装价格x为何值时,月利润的预报值最大?(参考数据
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9528e2da95b92a1d90b0f131cf865d1.png)
附:对于一组数据,其回归直线的斜率和截距的最小二乘估计分别为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8708c1c236608ff219c6077baaab3bbc.png)
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解题方法
【推荐1】已知
为数列
的前
项和,且
,
.
(1)求数列
的通项公式
;
(2)设
,记数列
的前
项和为
,求证:
.
![](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/039e4fe671d61e59b96ee525c9df43e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/246f3d8e556bb231cd884150bb22f55c.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acf900baf842cb410c1b7745f6eacd30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d7ac458288d8056bf2914ec95011fa5.png)
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解题方法
【推荐2】已知数列
的前
项和为
.
(1)求数列
的通项公式;
(2)设
为数列
的前
项和,其中
,求
;
(3)若存在
,使得![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d48f983ce2aed0f33880163994a83dc.png)
成立,求出实数
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/033aa83400bc9291900b425cfa3acfac.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da32e6c01e47e8c84a7ff44ac125a5a.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f66502169d7a5f5f36977cc885735d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1657428242d7760169a287042dc9e03e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
(3)若存在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e145b6046bc80d0ffecc61ac67c87ca1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d48f983ce2aed0f33880163994a83dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2813ebb59d6e01317bf802a08a1d00eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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