1 . 求函数
的定义域为R的充要条件.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71fce6d304120a8dc2c6b01da828b20a.png)
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2 . 下列命题正确的序号是__________ .
①命题“若
,则
”的否命题是真命题;
②命题“
、
都是偶数,则
是偶数”的逆否命题是真命题;
③若
是
的充分不必要条件,则
是
的必要不充分条件;
④方程
有唯一解的充要条件是
.
①命题“若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/432d77fe5ad3032d59a237dd94c8a638.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54969adfe007f7dacf556c4c863670b9.png)
②命题“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20d6fc9b90f370fbb27552876b650f8f.png)
③若
![](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/7ffc1bb9d53a27d484396ad74d6a26e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e26b38e357c7d985656ba7bb3c794a5.png)
④方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfb603ddbcd1297dfc9e08d33c360da6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b04b3794edcae853d076ac1df612eccf.png)
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