在等比数列
中,
.
(1)求
的通项公式;
(2)设
,数列
的前
项和
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76eedb8b626a77f8c26d2995bb37067c.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ea025149c457a3d5c6e508c82f7907f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.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/94351ce858fa3f3a09cfadc2d23d7253.png)
更新时间:2018-04-29 16:13:55
|
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解答题-问答题
|
较难
(0.4)
【推荐1】从数列
中取出部分项,并将它们按原来的顺序组成一个数列,称之为数列
的一个子数列,已知无穷等比数列
的公比为
.
(1)若
.
①求数列
的通项公式;
②若
分别为等差数列
的第
项和第
项,试求数列
的前
项和
.
(2)证明:当
时,数列
不存在无穷等差子数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eda159a2eefebf8954370f44df0935d9.png)
①求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eedd5b5ba81010aa9f45afbe62fa77e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d91e07104b699c4012be2d26160976a2.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/08eb71ecf8d733b6932f4680874dbbf3.png)
(2)证明:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b22c7f2a62647bacc914ee8525d1b07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
您最近一年使用:0次
解答题-问答题
|
较难
(0.4)
解题方法
【推荐2】已知
是不相等的正数,在
之间分别插入
个正数
和正数
,使
是等差数列,
是等比数列.
(1)若
求
的值;
(2)若
,如果存在
使得
,求
的最小值及此时
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20655342f9ace8b50a50f5eae6f37beb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0deee56cdb3d71a61f33763d350845a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344cf4e3f76485610c06ecac578fcaa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c52dd8d016bbb44d79ad41822313ae55.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59aaf088da5730d295f6aae8bf605ebb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c6ce02259a85ea191541f4a708738f1.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/774e0e9e80b4ddc64a82434aa4828866.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71942c9560b5789c8558f43d240b8470.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ca4ae8dc0a6859759d16555a7ed9c6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
您最近一年使用:0次
解答题-证明题
|
较难
(0.4)
名校
解题方法
【推荐1】已知数列
满足
,
.
(1)证明:数列
为递增数列.
(2)证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21567d7b82549773703f405aa983ec6b.png)
(3)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eac97c575cb54709f0b9ad23d49c0a95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ea8d0e50065114b05ef2dc1ea1129cf.png)
(1)证明:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21567d7b82549773703f405aa983ec6b.png)
(3)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/184aa60f6311a283ccd32204f5f51b7c.png)
您最近一年使用:0次
【推荐2】已知数列
满足
.
(1)求数列
的通项公式;
(2)设
,数列
的前
项和为
,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0451746d1582cf16235eef4087c5318.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b3e257a216cbe1a806f171d6dd08ca6.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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a206f906597710407346e83d3b0dd56.png)
您最近一年使用:0次