12-13高二下·辽宁沈阳·阶段练习
1 . 下列命题中,真命题的有 ______ .(只填写真命题的序号)
① 若
则“
”是“
”成立的充分不必要条件;
② 当
时,函数
的最小值为2;
③ 若命题“
”与命题“
或
”都是真命题,则命题
一定是真命题;
④ 若命题
:
,则
:
.
① 若
![](https://img.xkw.com/dksih/QBM/2013/3/28/1571166311596032/1571166317133824/STEM/2877a29ce6a2476f82bb2c4eed98e830.png?resizew=71)
![](https://img.xkw.com/dksih/QBM/2013/3/28/1571166311596032/1571166317133824/STEM/ca78962477b34cb4af1d45d93e0e2d5b.png?resizew=67)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/432d77fe5ad3032d59a237dd94c8a638.png)
② 当
![](https://img.xkw.com/dksih/QBM/2013/3/28/1571166311596032/1571166317133824/STEM/5886572a0f72455ebc0275f45c2f3be9.png?resizew=67)
![](https://img.xkw.com/dksih/QBM/2013/3/28/1571166311596032/1571166317133824/STEM/4fa94ead22ae4cdc8a95141248511922.png?resizew=108)
③ 若命题“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ffc1bb9d53a27d484396ad74d6a26e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
④ 若命题
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daa4f0a12223f1e1171af131b71a08ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ffc1bb9d53a27d484396ad74d6a26e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aeaf0c7c8aac29d2b3704f4416724567.png)
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