题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085536-33604.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-35783.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-35783.png)
(2)试确定x,使修建此矩形场地围墙的总费用最小,并求出最小总费用.
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-62402.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-61019.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-42633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-50690.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085538-93809.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085538-32856.png)
解析
试题分析:(1)根据条件可以将所有墙的长度都用含
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085538-35880.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085538-26061.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085539-83333.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-62402.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085539-29822.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085539-22206.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-61019.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-50690.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-35783.png)
(1)画出如下示意图,由矩形的面积为S,可知与
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085539-13524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085540-39300.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085540-43902.png)
显然
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085540-27347.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-62402.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085540-85083.jpg)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085540-61042.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085541-95627.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-35783.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085541-35567.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085541-21511.png)
若
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085541-29644.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-61019.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085541-99623.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085542-37829.png)
若
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085542-33044.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085537-50690.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085538-93809.png)
最小总费用为
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085542-89644.png)
核心考点
试题【修建一个面积为平方米的矩形场地的围墙,要求在前面墙的正中间留一个宽度为2米的出入口,后面墙长度不超过20米,已知后面墙的造价为每米45元,其它墙的造价为每米18】;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/20191018/20191018085530-46154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085530-18566.png)
A.{x|x<1} | B.{x|-1<x<1} | C.{x|x<-1或x>1} | D.{x|x>1} |
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085523-35091.jpg)
A.f(b)>f(c)>f(d) | B.f(b)>f(a)>f(e) |
C.f(c)>f(b)>f(a) | D.f(c)>f(e)>f(d) |
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085451-75551.png)
(1)求f(x)的单调区间和极值;
(2)关于
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085451-76622.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085451-63260.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085439-45982.png)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085439-16839.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085439-21668.png)
(2)若函数
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085439-64386.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085439-78461.png)
(3)a、b是函数
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085440-73802.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085440-88261.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085440-57274.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191018/20191018085440-44466.png)
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