解题方法
1 . 给出下列说法:
①数列
,
,
,
,
…的一个通项公式是
;
②当
时,不等式
对一切实数x都成立;
③函数
是周期为
的奇函数;
④两两相交且不过同一点的三条直线必在同一个平面内.
其中,正确说法序号是_________ .
①数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30b12efb03327f461e868b2ea433f9b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ce0249a3ff99c083fa4421877549db1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adbd3e8cf8325999cde03adf845d3dd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daf4e57a8023222d2cdf88fad75ac496.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47212543d8a4ecf45f9509fe5ab8733b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b6d03dfc5b4ce38e17403b3b49fdc15.png)
③函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8250a1f5d4211d5dc1f47e1855245916.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
④两两相交且不过同一点的三条直线必在同一个平面内.
其中,正确说法序号是
您最近一年使用:0次