解题方法
1 . 给出下列四个命题:
①若
,则
;
②当
时,
的最小值为4;
③已知
是等差数列
的前
项和,若
,则
;
④过抛物线
焦点
的直线交抛物线于
两点,则
.
其中正确命题的序号为___________ .
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bed0d3e6741e0193addff8cf7b25019c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a68265211ff8205d5c0ea1b5f7e20521.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/409d37d9465ec42be99d13cfbc0bc6b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70ced225ea5590e06ece27b77ad3ac74.png)
③已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b28ef6f1b2279af482557a8ea46f2e43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a425978da20cebf8c4c63953579e7b35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6745b23f90d2e3a2bad6048bc734bb08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47af0fa1a8a597e0d1336a5368f47084.png)
④过抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf7b911d5ec34e3ffc72b89285592ff3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/655b6a742dbacdab5aaa298007663dd4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0a415f13ef220884d1916203ed4e542.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/669b5240185e8caf113d2b5fb6a453ae.png)
其中正确命题的序号为
您最近一年使用:0次