【题文】函数,其中,则该函数的值域为
【题文】函数,其中,则该函数的值域为
题型:难度:来源:
【题文】函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092449-79050.png)
,其中
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092449-99967.png)
,则该函数的值域为
.
答案
【答案】
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092449-15797.png)
解析
【解析】函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092449-79050.png)
的对称轴为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092450-13846.png)
,
所以当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092450-18077.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092450-80403.png)
有最小值为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092451-83282.png)
,
当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092451-68205.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092450-80403.png)
有最大值为21,
所以该函数的值域为
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092449-15797.png)
.
举一反三
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092438-25005.png)
,则函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092439-39709.png)
的值为________
【题文】函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092424-30555.png)
的零点
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092424-14214.png)
( )
【题文】函数
f(
x)=
x2+2(
a-1)
x+2在区间(-∞,4]上递减,则
a的取值范围是( )
A.![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092402-82174.png) | B.(-∞,-3) | C.(-∞,-3] | D.[3,+∞) |
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092351-83131.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092351-34241.png)
(
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092351-43686.png)
),若
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092352-29270.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092352-57026.png)
,使得
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092352-57524.png)
,则实数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327092352-60513.png)
的取值范围是 ( )
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