题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091313-21159.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091313-99688.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091313-27254.png)
试求:(1)函数f(t)的定义域;
(2)函数f(t)的最小值.
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091314-83531.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091314-30380.png)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091314-56111.png)
据题意知
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091315-65435.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091315-79839.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091315-55783.png)
由于
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091315-77123.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091316-51010.png)
因为
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091316-13004.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091316-21009.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091316-20728.png)
因为F点在BC上,所以
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091316-49024.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091317-29564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091317-76943.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091317-22941.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091317-26547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-38747.png)
于是有
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-93635.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-11245.png)
故函数f(t)的定义域为
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091314-83531.png)
(2) 由(1)得
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-54040.png)
令
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-89731.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091319-12633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091319-73046.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091319-70736.png)
因此当
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091319-33713.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-89731.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091320-88271.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-89731.png)
即
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091320-31524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091318-89731.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091314-30380.png)
【命题意图】本题考查函数的定义域,值域,二倍角公式,利用导数求函数最值等知识 ,意在考查学生的抽象概括能力,运算求解能力.
核心考点
试题【(本小题满分14分)矩形纸片ABCD的边AB=6,AD=10,点E、F分别在边AB和BC上(不含端点). 现将纸片的右下角沿EF翻折,使得顶点B翻折后的新位置B】;主要考察你对函数的单调性与导数等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091300-58855.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-40285.png)
(2)是否存在
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-86564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-20348.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-87952.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-86564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-20348.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-87952.png)
(3)若不等式
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091301-82995.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091302-55919.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091302-86711.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091252-33205.png)
(1)若f(x)在[1,+∞)上单调递增,求a的取值范围.
(2)若定义在区间D上的函数y=f(x)对于区间D上的任意两个值x1,x2总有不等式
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091252-45311.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091253-66707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091244-95845.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091245-85892.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091245-18822.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091245-40691.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091245-37835.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091245-56244.png)
的解集为
A.![]() | B.(![]() ![]() |
C.(![]() ![]() | D.(![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091240-43420.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091240-92088.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091232-21687.png)
(1)证明函数
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091232-71170.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091232-57220.png)
(2)用反证法证明方程
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018091232-43886.png)
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