1 . 若函数
的导函数
在点
可导,则称
在点
的导数值为
在点
的二阶导数,记作
.若
在开区间I内的每一点都二阶可导,则得到一个定义在I上的二阶导函数,记作
.曲线
上任意两点间的弧段总在这两点的下方;而曲线
则相反,任意两点间的弧段总在这两点连线的上方.我们把具有前一种特性的曲线称为凸的,相应的函数称为凸函数;后一种曲线称为凹的,相应的函数称为凹函数.连续曲线上凹弧与凸弧的分界点称为曲线的拐点.拐点在统计学,物理学,经济学领域都有重要的应用.若函数
在定义域内是一条连续不断的曲线,对任意的
,
的导函数
都存在,且
的导函数
也都存在,若
,使得
,且在
的左右附近,
异号,则称点
为曲线
的拐点.已知函数
,
,
.
(1)求
在定义域内的拐点个数;
(2)若
在
上有唯一拐点
,求实数k的取值范围;
(3)函数
在区间
恰有一个拐点,求实数a的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a4b04824a308519a61318a82aa97a05.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a4b04824a308519a61318a82aa97a05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79b752f0f189e5d8666daea73e145dff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79b752f0f189e5d8666daea73e145dff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aac282e92da3691942a6ba8511de2303.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aac282e92da3691942a6ba8511de2303.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344ccbf79da6ad7e3709d6fa72efb756.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aef469c7b7cb9945b984222381b9c000.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/268ea7b6a873194253b75233ac18545a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a4b04824a308519a61318a82aa97a05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a4b04824a308519a61318a82aa97a05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aac282e92da3691942a6ba8511de2303.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a09c048d8ea4456b9db662b39d3a208.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd16646e695eeb7088134cb94d51691.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79b752f0f189e5d8666daea73e145dff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aac282e92da3691942a6ba8511de2303.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8559f5db9b978cb2bd290dbce7268629.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2430fa48f248e998e256e91165970bbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d74fb771e771f22b7e4249da06289e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3a63eed6f348f10044c48dacb045b7b.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be1ce3f01e2b6364f9a9fdaf197d5e29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/870ebc2f7aabb028024894568d749934.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3ac8b888cea3c2a212f4b21447d3bd.png)
(3)函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2629d7ba67bc8caed81c64c3c1341275.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc6554ac3dff4a59833e407db887f6e6.png)
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