【题文】设f(x)是R上的奇函数,当x>0时,f(x)=2x+x,则当x<0时,f(x)=( )A.-(-)x-xB.-()x+xC.-2x-xD
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【题文】设f(x)是R上的奇函数,当x>0时,f(x)=2
x+x,则当x<0时,f(x)=( )
A.-(- )x-x | B.-( )x+x |
C.-2x-x | D.-2x+x |
答案
【答案】B
解析
【解析】当x<0时,则-x>0,
∴f(-x)=2
-x-x.又f(x)为奇函数,
∴f(x)=-f(-x)=-(
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002634-80191.gif)
)
x+x.故选B.
举一反三
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002615-38960.png)
是
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002615-73013.png)
上的奇函数.当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002615-67150.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002615-32327.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002616-70824.png)
的值是( )。
【题文】设f(x)是R上的奇函数,当x>0时,f(x)=2
x+x,则当x<0时,f(x)=( )
A.-(- )x-x | B.-( )x+x |
C.-2x-x | D.-2x+x |
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002355-45219.png)
是
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002355-43821.png)
上的奇函数.当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002355-74594.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002356-17794.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002356-13172.png)
的值是( )。
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002347-25223.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002347-91840.png)
,若当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002347-89883.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002348-91923.png)
恒成立,则实数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002348-29373.png)
的取值范围是
【题文】已知函数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002317-60965.png)
,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002317-10524.png)
,若当
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002318-54584.png)
时,
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002318-85968.png)
恒成立,则实数
![](http://img.shitiku.com.cn/uploads/allimg/20200327/20200327002318-83244.png)
的取值范围是
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