已知函數(shù)f(x)=|x+1|+|x-1|(x∈R).
![](http://hiphotos.baidu.com/zhidao/pic/item/d043ad4bd11373f0784bab2ea70f4bfbfbed040f.jpg)
(1)證明:f(x)函數(shù)是偶函數(shù);
(2)利用絕對(duì)值及分段函數(shù)知識(shí),將函數(shù)解析式寫(xiě)成分段函數(shù),然后在給定的坐標(biāo)系中畫(huà)出函數(shù)圖象;
(3)寫(xiě)出函數(shù)的值域.
![](http://hiphotos.baidu.com/zhidao/pic/item/c2fdfc039245d6880e0a7615a7c27d1ed21b2473.jpg)
證明:(1)因?yàn)楹瘮?shù)y=f(x)的定義域?yàn)镽,
且f(-x)=|-x+1|+|-x-1|=|x-1|+|x+1|=f(x),所以f(x)是偶函數(shù);
(2)
f(x)= | ?2x(x<?1) | 2(?1≤x≤1) | 2x(x>1) |
| |
(3)函數(shù)的值域?yàn)椋篬2,+∞).