【题文】已知,且,则A的值是( )A.15B.C.±D.225
【题文】已知,且,则A的值是( )A.15B.C.±D.225
题型:难度:来源:
【题文】已知
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042048-61441.png)
,且
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042049-72098.png)
,则A的值是( )
A.15 | B.![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042049-53067.png) | C.±![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042049-53067.png) | D.225 |
答案
【答案】B
解析
【解析】
试题分析:由
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042048-61441.png)
得到
代入到
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042049-72098.png)
得:
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042049-99808.png)
,
利用换底法则得到
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042050-38487.png)
,所以
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042050-84460.png)
故选B
考点:指数函数综合题.
举一反三
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042039-29542.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328042039-28870.png)
=
.
【题文】化简
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328041532-78303.png)
的结果为( )
【题文】若
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328041309-86327.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328041309-69631.png)
的表达式为( )
【题文】设
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328041256-72963.png)
,则
![](http://img.shitiku.com.cn/uploads/allimg/20200328/20200328041256-93856.png)
的大小关系是( )
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