题目内容
某
企
业拟建造如图所示的容器(不计厚度,长度单位:米),其中容器的中间为圆柱形,左右两端均为半球形,按照设计要求容器的体积为
立方米,且
.假设该容器的建造费用仅与其表面积有关.已知圆柱形部分每平方米建造费用为3千元,半球形部分每平方米建造费用为
.设该容器的建造费用为
千元.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231831392823812.jpg)
(Ⅰ)写出![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139266310.png)
关于
的函数表达式,并求该函数的定义域;
(Ⅱ)求该容器的建造费用最小时的
.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139172156.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139188164.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139204564.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139219469.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139235484.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139266310.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231831392823812.jpg)
(Ⅰ)写出
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139266310.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139313172.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139328260.png)
(Ⅱ)求该容器的建造费用最小时的
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139328260.png)
(1)![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139360325.png)
+
,定义域为(0,
).
(2)
米时,
该容器的建造费用最小.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139360325.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139375783.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139391522.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139406398.png)
(2)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139422712.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139438172.png)
(Ⅰ)因为容器的体积为
立方米,所以![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139469770.png)
,解得
,所以圆柱的侧面积为
=![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139547977.png)
,两端两个半球的表面积之和为
,所以![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139360325.png)
+
,定义域为(0,
).
(Ⅱ)因为![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139656352.png)
+
=
,所以令
得:
; 令
得:
,所以
米时,
该容器的建造费用最小.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139204564.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139469770.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139204564.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139516803.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139531497.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139547977.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139562890.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139578483.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139360325.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139375783.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139391522.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139406398.png)
(Ⅱ)因为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139656352.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139672759.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139687482.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139718989.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139734439.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139750739.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139765430.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139781814.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139422712.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823183139438172.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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