【题文】不等式的解集为,那么 (
题型:难度:来源:
【题文】不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075422-21562.png)
的解集为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075423-93068.png)
,那么 ( )
答案
【答案】A
解析
【解析】
试题分析:∵不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075422-21562.png)
的解集为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075423-93068.png)
,∴一元二次函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075425-76034.png)
开口向下且恒在x轴下方,∴
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075423-35127.png)
,故选A
考点:本题考查了一元二次不等式恒成立
点评:熟练掌握一元二次不等式恒成立的转化法则是解决此类问题的关键,属基础题
举一反三
【题文】已知不等式ax
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075357-45802.png)
+bx+1<0的解集为{x|-1<x<2},则ab=
A.-1 | B.-![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075358-22102.png) | C.-![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075358-58707.png) | D.1 |
【题文】不等式
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075339-74057.png)
的解集为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075339-43360.png)
,那么 ( )
【题文】已知不等式ax
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075243-29104.png)
+bx+1<0的解集为{x|-1<x<2},则ab=
A.-1 | B.-![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075243-29285.png) | C.-![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327075243-71317.png) | D.1 |
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