题目
题型:解答题难度:一般来源:不详
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-61195.png)
(1) 当
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-62853.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
(2) 是否存在这样的实数a,使得函数
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-23470.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-52028.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36636.png)
解析
试题分析:(1)首先根据对数函数的底数
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36976.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-34779.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-13643.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-74519.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36976.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-34779.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-23470.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-68174.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-23008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-24762.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-44492.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-23008.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-44492.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-44492.png)
试题解析:(1)∵
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36976.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-34779.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-34779.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-62853.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-13643.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-62853.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-62853.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-74519.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-89197.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36976.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-23906.png)
(2)令
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-34779.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-68174.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-92534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-92773.png)
又∵
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-23470.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-68174.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-23008.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154700-91594.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154659-92773.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154700-68686.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154700-71885.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154656-12104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154700-43704.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154658-24762.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154700-35816.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154657-36636.png)
核心考点
试题【已知函数.(1) 当时,函数恒有意义,求实数a的取值范围;(2) 是否存在这样的实数a,使得函数在区间上为增函数,并且的最大值为1.如果存在,试求出a的值;如果】;主要考察你对对数函数的定义等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154654-69271.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154654-45655.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154651-73157.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154652-53042.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154642-81854.png)
(2)已知集合
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154642-27773.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154642-15453.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154643-19548.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154643-26786.png)
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154639-21094.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20190820/20190820154637-97016.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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