解:(1)法一:因为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939870906.png)
是奇函数,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939885626.png)
即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939917865.png)
,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939932361.png)
………………………………………………2分
又
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939761447.png)
的图象经过点(1,3)和(2,3),
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232049399791518.png)
,解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940010606.png)
。………………………………………4分
所以,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940026723.png)
。……………………………………………………5分
法二:因
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939729907.png)
是奇函数,且其图象经过点(1,3)和(2,3)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232049400571992.png)
…………………………………………………3分
解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940073742.png)
……………………………………………………………………4分
所以,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940026723.png)
………………………………………………………5分
(2)任取
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940119664.png)
,有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232049401352534.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940151942.png)
……………………………………………………………………9分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940166699.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940182848.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232049402131317.png)
,即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940229652.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204940244195.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939761447.png)
在
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939807493.png)
上是减函数.……………………………………………………………11分
(3)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939761447.png)
在
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823204939839510.png)
上是减函数.…………………………………………………………13分