名校
1 . 有以下结论:
①不存在
,使得
;
②若
,则a,x,b成等比数列;
③设O是平面ABC内一定点,P为平面ABC内一动点,若
,则O为
的外心;
④已知
所在的平面上的点P满足
,则直线AP一定经过
的内心.
其中正确的结论序号为______ (请把所有正确的结论序号都写出来).
①不存在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e36c9c91220b0f2cbd4a48e8fa90e3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69b682778d7f3b4bb6e0950de69453c3.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99047070ae53baae5a237f7fc510db89.png)
③设O是平面ABC内一定点,P为平面ABC内一动点,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af1983fa9be423eecc616de136bb1d35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
④已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8908bb969d28eb473a60c9e8f4073e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
其中正确的结论序号为
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名校
解题方法
2 . 给出以下几个结论:
①若等比数列
前n项和为
,
,则实数
;
②若数列
,
的通项公式分别
,
,且
,对任意
恒成立,则实数a的取值范围是
;
③设在
中,内角A、B、C的对边分别为a、b、c,且
,则
的最大值为
;
④在
中,三内角A,B,C所对的边分别为a,b,c,则
;
其中正确结论的序号为______ .
①若等比数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97b794ed9de8e93de6e067c3d0259558.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e145b6046bc80d0ffecc61ac67c87ca1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b108ab31cc093f03cf48ad65429889e.png)
②若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20ae956b7c89f63fcb27a507c9728344.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6dc7eb66f5d777c283a395eda5635d4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83ac679ad239090a6ce21a10b47e332c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e145b6046bc80d0ffecc61ac67c87ca1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54c30f7465c99d88caf6703bc7365a51.png)
③设在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1f32fe2cea6b046da549c0d04e103e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/afd0b09f2c1c75840f0a1a1eb3528ae3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/827ccf0c04aa941ba20d5f4c6068b46b.png)
④在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d22b0c674439368ca4d402fe8ce0888.png)
其中正确结论的序号为
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3 . 已知
为数列
的前
项和,且
,
(
).给出下列3个结论:①数列
一定是等比数列;②若
,则
;③若
,
,
成等比数列,则
.其中,所有正确结论的序号为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f17a7b5a8970e7e8da883b2e93d3698.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7fab51121848ce166035ceab6f4e00b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10bbdef421c976962a270a2beabbad91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc6409c388f766ff05be0e5d080bed2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8a1d093160d34fe50bbcedff8f5bc12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/001d1773df6520fba1d44007fe942836.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1ccc6c74b8754e9bcbb3f39a11b6f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da4cd81500bdb43118150dbdb1541e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc858b7a95c5006a44067022da09f667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b9f0255df77526718a46c4e78b78513.png)
A.② | B.②③ | C.①③ | D.①②③ |
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