1 . 判断下列对应是不是从集合A到集合B的映射,其中哪些是一一映射?哪些是函数?为什么?
(1)A={1,2,3,4},B={3,4,5,6,7,8,9},对应关系f:x→2x+1;
(2)A={平面内的圆},B={平面内的矩形},对应关系是“作圆的内接矩形”;
(3)A={1,2,3,4},B={1,
,
,
},对应关系f:x→y=
.
(1)A={1,2,3,4},B={3,4,5,6,7,8,9},对应关系f:x→2x+1;
(2)A={平面内的圆},B={平面内的矩形},对应关系是“作圆的内接矩形”;
(3)A={1,2,3,4},B={1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf35027e76f8ea593f82023973d4aba3.png)
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2010·北京海淀·二模
名校
2 . 给定集合
,映射
满足:
①当
时,
;
②任取
若
,则有![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
.
.则称映射
:
是一个“优映射”.例如:用表1表示的映射
:
是一个“优映射”.
表1 表2
(1)已知表2表示的映射
:
是一个优映射,请把表2补充完整(只需填出一个满足条件的映射);
(2)若映射
:
是“优映射”,且方程
的解恰有6个,则这样的“优映射”的个数是_____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe05c3181726d202d021050807378989.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92185b667af21e649c9b071042d29af0.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7873a6c263a103ce7a7b1410222bd245.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e2c865ebac120a4d1e17838ac9dc0ed.png)
②任取
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea0eb2f420c6146a0809f01cb3168f49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72ac49ab7c8001c209b8611b9ea40d85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f1cd15d46d4fc519ea93da0a7a82a01.png)
.则称映射
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4ff0af96ea467337cb30c4c765b5f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22c3373a475f821448143d482d7c0a35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4ff0af96ea467337cb30c4c765b5f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fea9eeefda7a3bfe23534700357fbacc.png)
表1 表2
![]() | 1 | 2 | 3 | |
![]() | 2 | 3 | 1 | |
![]() | 1 | 2 | 3 | 4 |
![]() | 3 |
(1)已知表2表示的映射
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4ff0af96ea467337cb30c4c765b5f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe7704aeb096266ab863326b66111d4.png)
(2)若映射
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4ff0af96ea467337cb30c4c765b5f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bf5648713989066021d4f7cd433727b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/987c640c84d230463ead6415c4c06a72.png)
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