题目内容
某种海洋生物身体的长度
(单位:米)与生长年限t(单位:年)
满足如下的函数关系:
.(设该生物出生时t=0)
(1)需经过多少时间,该生物的身长超过8米;
(2)设出生后第
年,该生物长得最快,求
的值.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356906474.png)
满足如下的函数关系:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356921840.png)
(1)需经过多少时间,该生物的身长超过8米;
(2)设出生后第
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356937319.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356953708.png)
(1)6年;(2)4或5.
试题分析:(1)求需经过多少时间,该生物的身长超过8米,实质就是解不等式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356984915.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356999623.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357015653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357015653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356937319.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240323570621077.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240323570771149.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357093560.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357015653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357124164.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240323571401217.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357155295.png)
试题解析:(1)设
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356984915.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357187579.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357202414.png)
即该生物6年后身长可超过8米; 5分
(2)设第
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357218674.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240323572332621.png)
令
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357249550.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357249588.png)
令
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240323572652062.png)
等号当且仅当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357280500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357296511.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357311583.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357327493.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357327551.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032356937319.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357358967.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824032357389355.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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