c90122
幼苗
共回答了26个问题采纳率:88.5% 举报
已知函数
![](https://img.yulucn.com/upload/e/78/e78e855cb5cf92b2b706bb4ac134eeeb_thumb.jpg)
(
![](https://img.yulucn.com/upload/1/0d/10d4a731b1cf36b629b958fbf90454fc_thumb.jpg)
),则()
A.
![](https://img.yulucn.com/upload/1/1e/11ece1253b9e042d0fb351a96a72f508_thumb.jpg)
必是偶函数
B.当
![](https://img.yulucn.com/upload/e/11/e119b60ed05b3ff29d666725cc102af8_thumb.jpg)
时,
![](https://img.yulucn.com/upload/e/e5/ee5fe466b8fc57d4ca848296d044bf41_thumb.jpg)
的图象必须关于
![](https://img.yulucn.com/upload/f/2b/f2b3960b7984e304a89178aca3cce6fd_thumb.jpg)
直线对称;
C.
![](https://img.yulucn.com/upload/e/e5/ee5fe466b8fc57d4ca848296d044bf41_thumb.jpg)
有最大值
D.若
![](https://img.yulucn.com/upload/5/09/5096a36454f0fb201978c56f8f8a1041_thumb.jpg)
,则
![](https://img.yulucn.com/upload/e/e5/ee5fe466b8fc57d4ca848296d044bf41_thumb.jpg)
在区间
![](https://img.yulucn.com/upload/a/ab/aab496f11776c11d9864a5b2d2f0aa01_thumb.jpg)
上是增函数;
D
试题分析:在二次函数上加绝对值符号,相当于把原二次函数在
![](https://img.yulucn.com/upload/8/36/83660ce05e8f651bbba89207b8a655d5_thumb.jpg)
轴下方的图像翻折到上方,原来处于
![](https://img.yulucn.com/upload/8/36/83660ce05e8f651bbba89207b8a655d5_thumb.jpg)
轴上方的图像保持不变.
当
![](https://img.yulucn.com/upload/2/17/217c37bd70b31390c9b393e1f6b893c5_thumb.jpg)
时画图可知
![](https://img.yulucn.com/upload/1/1e/11ece1253b9e042d0fb351a96a72f508_thumb.jpg)
不是偶函数,比如
![](https://img.yulucn.com/upload/e/cd/ecde3fdbc8bf93a6c709e999154a5b15_thumb.jpg)
就不是偶函数,排除A;
仅有
![](https://img.yulucn.com/upload/e/11/e119b60ed05b3ff29d666725cc102af8_thumb.jpg)
无法说明
![](https://img.yulucn.com/upload/1/1e/11ece1253b9e042d0fb351a96a72f508_thumb.jpg)
的图像关于
![](https://img.yulucn.com/upload/f/2b/f2b3960b7984e304a89178aca3cce6fd_thumb.jpg)
直线对称,比如
![](https://img.yulucn.com/upload/a/00/a00d0f782d5456a4747e567ef1855439_thumb.jpg)
满足
![](https://img.yulucn.com/upload/e/11/e119b60ed05b3ff29d666725cc102af8_thumb.jpg)
但画图可知图像并不关于
![](https://img.yulucn.com/upload/f/2b/f2b3960b7984e304a89178aca3cce6fd_thumb.jpg)
直线对称,排除B;
![](https://img.yulucn.com/upload/1/1e/11ece1253b9e042d0fb351a96a72f508_thumb.jpg)
的图像两边向上无限延伸,没有最大值,排除C;
若
![](https://img.yulucn.com/upload/5/09/5096a36454f0fb201978c56f8f8a1041_thumb.jpg)
,则函数
![](https://img.yulucn.com/upload/6/01/60145a12b69d0a3e3f90352c367faa76_thumb.jpg)
于
![](https://img.yulucn.com/upload/8/36/83660ce05e8f651bbba89207b8a655d5_thumb.jpg)
轴最多有一个交点,故恒有
![](https://img.yulucn.com/upload/5/1a/51ac9261a2c82f6e9c1b4972ef6886b8_thumb.jpg)
,因此
![](https://img.yulucn.com/upload/9/72/97222f784d7b55638d1f4ba9d43422e6_thumb.jpg)
,其对称轴为
![](https://img.yulucn.com/upload/4/39/4390d649294378e7c1dcb8efbbca3e47_thumb.jpg)
,开口向上,因此
![](https://img.yulucn.com/upload/e/e5/ee5fe466b8fc57d4ca848296d044bf41_thumb.jpg)
在区间
![](https://img.yulucn.com/upload/a/ab/aab496f11776c11d9864a5b2d2f0aa01_thumb.jpg)
上是增函数,D正确.
1年前
6