名校
解题方法
1 . 数列
满足
则称数列
为下凸数列.
(1)证明:任意一个正项等比数列均为下凸数列;
(2)设
,其中
,
分别是公比为
,
的两个正项等比数列,且
,证明:
是下凸数列且不是等比数列;
(3)若正项下凸数列的前
项和为
,且
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a0bee75d4d83c0b76421fd87113e4dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(1)证明:任意一个正项等比数列均为下凸数列;
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f67fc95a626251da11649acb5e1706f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b783cf91e34e692ce8e171f0965cb53f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c340d7d093dd4a275ffea4b87cd26827.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6268630d5e5288048d32f4aa5c8bc02d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c171ff5c2728e7cf00a88f88de14f308.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3755d7aa870e2f199d6c12264fc9be86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
(3)若正项下凸数列的前
![](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/0002f427eded1721f43d60dd0fd3ffe0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd419dc0a6580ab97777b2cb8fd7cded.png)
您最近一年使用:0次
2024-06-12更新
|
1136次组卷
|
5卷引用:福建省龙岩市上杭县第一中学2024届高三下学期5月数学模拟试题
名校
解题方法
2 . 如图,在正方体
中,E,F是底面正方形
四边上的两个不同的动点,过点
的平面记为
,则( )
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/be42cb24-a40c-4f8d-af2f-c2e172820934.png?resizew=160)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fd191d81c6f35dc5a014872771673c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/be42cb24-a40c-4f8d-af2f-c2e172820934.png?resizew=160)
A.![]() |
B.当E,F分别是![]() ![]() ![]() |
C.当E,F分别是![]() ![]() ![]() |
D.当F是![]() ![]() |
您最近一年使用:0次
2022-12-03更新
|
1594次组卷
|
4卷引用:福建省上杭县第一中学2023届高三上学期12月月考数学试题
名校
3 . 已知抛物线C:
过点
,焦点为F,准线与x轴交于点T,直线l过焦点F且与抛物线C交于P,Q两点,过P,Q分别作抛物线C的切线,两切线相交于点H,则下列结论正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fc58c62444bf42a25289c45425a00f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3247f03357462fec934f37c65ebdc77e.png)
A.![]() | B.抛物线C的准线过点H |
C.![]() | D.当![]() ![]() |
您最近一年使用:0次
2022-11-18更新
|
1569次组卷
|
3卷引用:福建省龙岩第一中学2022-2023学年高二上学期第三次月考数学试题