名校
解题方法
1 . 设连续函数
的定义域为
,如果对于
内任意两数
,都有
,则称
为
上的凹函数;若
,则称
为凸函数.若
是区间
上的凹函数,则对任意的
,有琴生不等式
恒成立(当且仅当
时等号成立).
(1)证明:
在
上为凹函数;
(2)设
,且
,求
的最小值;
(3)设
为大于或等于1的实数,证明:
.(提示:可设
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f030c36bb8786df88d401792062a4100.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f030c36bb8786df88d401792062a4100.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ce7ae90d808f05e86ea063238e4b2f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a7a1783349936cc7254a4a8694c6812.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f030c36bb8786df88d401792062a4100.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1bedaf3854b48806b82b3b804451cf8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f030c36bb8786df88d401792062a4100.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0fec4d10407498ec4692b33ebe1bb7d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a1784a3a9dd90c51dab965445d65f08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2697ef67790838c84cc238a0334c5d47.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/008ab9b6200370bd8d534a6317cb88e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7160d93f92089ef36f3dab809d3114b8.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6da13af19b32430759c9c1d1aea894e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b16ad49f62d7362441e3b92efe7f87d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b47ade684a2e49ef6139afe6ab59a29.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1d4c274b53adfbffc4b19e7adbc39d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6694499b581256296277c515f6dcdc8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10cda4049695561dab3e0803c3a287fe.png)
您最近一年使用:0次
解题方法
2 . 已知函数
,其中
.
(1)当
时,若
,求
的值;
(2)证明:
;
(3)若函数
的最大值为
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f40b7076417a2d9a77657020cd3d0d1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fadd2e6f0aa16c2c466c904474ffc79c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9920ba41061fb4971be07bda1ddfb2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a0698b324aad6962f9f50b240cffe48.png)
(3)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad3125c342e7fcc6ba0aff633dbaf8d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95bacae35b6e16a0a33c2bdc6bc07df7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
3 . 已知
的三边长
,三内角为
.求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7f5573b30734d65648f61c0a94c98de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38335830b93ac4d99c28a8e209eecb3f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b102b36cba4c1868afcd7a591a796da.png)
您最近一年使用:0次