【题文】(本题满分10分)已知全集,,若,求的值.
【题文】(本题满分10分)已知全集,,若,求的值.
题型:难度:来源:
【题文】(本题满分10分)已知全集
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134040-48488.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134040-75578.png)
,若
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-40080.png)
,求
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-43675.png)
的值.
答案
【答案】
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-76815.png)
.
解析
【解析】
试题分析:因为
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134040-48488.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-40080.png)
,所以
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134042-97030.png)
且
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134042-20106.png)
于是
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134043-92302.png)
或
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-76815.png)
,检验当
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134043-48064.png)
时,是否符合题意.
试题解析:由条件可知:
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134042-97030.png)
且
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134042-20106.png)
,于是
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134043-92302.png)
或
若
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134043-39704.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134044-77182.png)
不合题意,舍去
若
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-76815.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134044-63961.png)
满足题意
综上所述
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134041-76815.png)
考点:1.集合的运算;2.一元二次方程的解法.
举一反三
【题文】(本题满分12分)已知不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134031-24805.png)
的解集是A,不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134032-52421.png)
的解集是B,若不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134032-77215.png)
的解集是
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134032-96560.png)
,则:
(1)求 A, B,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134032-96560.png)
;
(2)求
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134032-88131.png)
。
【题文】已知集合
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134014-50404.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134014-71707.png)
,在区间
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134014-58792.png)
上任取一实数
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134014-31526.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200322/20200322134015-49085.png)
的概率为
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