1 . 设12元实数集合
满足:可将其划分为两个6元子集
和
,使得对每个
,均有
,则这样的
可以是______ .(写出一个即可)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab68ee11734bd89733c3064af16cea50.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fe342a96adffebbb5d59c5fcfd138e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fde1b1e2b446a4db8650c9fdab83766.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff197132463fd76db478b76ed2cf653c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/908fbdc652b3cafc1f4d0b2e3ae2a094.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
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2 . 两个集合
和
之间若存在一一对应关系,则称
和
等势,记为
.例如:若
为正整数集,
为正偶数集,则
,因为可构造一一映射
.下列说法中正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6c4704f64d12d5a12d7470eb02dc2c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6c4704f64d12d5a12d7470eb02dc2c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d63694528f708717928d3431ad0f0893.png)
A.两个有限集合等势的充分必要条件是这两个集合的元素个数相同 |
B.对三个无限集合![]() ![]() ![]() ![]() ![]() ![]() |
C.正整数集与正实数集等势 |
D.在空间直角坐标系中,若![]() ![]() ![]() ![]() ![]() |
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