解题方法
1 . 给出下列命题
(1)命题“
,
”的否定是“
,
”
(2)若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b804002ee3d72ff947cfc8426f90047c.png)
(3)已知
,
,若
,则a的取值范围是![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a568a870b0c247e1abaf4bf65b83865.png)
其中正确命题的序号为( )
(1)命题“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ad5fe274cfc8da2dacfb65801f344ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9490565d4714ffcbadb26fdfca443856.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ccd7af9298cd5ff19d8866fedb42ec4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9490565d4714ffcbadb26fdfca443856.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b804002ee3d72ff947cfc8426f90047c.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0820285d82c98efc92ee43db58418fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f4cde12869125b1eebc2c6c8ae22cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96f1ba0a1129741502600e47bf058c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a568a870b0c247e1abaf4bf65b83865.png)
其中正确命题的序号为( )
A.(2)(3) | B.(2) | C.(1)(3) | D.(1)(2) |
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