1 . 已知函数
,记
的图象为曲线C.
(1)若以曲线C上的任意一点
为切点作C的切线,求切线的斜率的最小值;
(2)求证:以曲线C上的两个动点A,B为切点分别作C的切线
,
,若
恒成立,则动直线AB恒过某定点M.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/847cc4ad8e1058e49563117ef0a9f65c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
(1)若以曲线C上的任意一点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/caf0d139c9810361b4971904a943856b.png)
(2)求证:以曲线C上的两个动点A,B为切点分别作C的切线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9b0f5f44abbc6544a2f672b025b013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f6f17bc385bafb37e8f964e5eb99cd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1095c036b49c3327baaa2c3c7f746134.png)
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2 . 设函数
.
(1)当
时,
的最小值为5,求
的值:
(2)当
时,设
是函数
图象上的两个动点,且在A,B处的两切线
互相平行,求证:直线AB必过定点,并求出此定点的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57363b27165d20f8aca704f33e5bb0b2.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/538193a4717d564c01145e82314c2d1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b108ab31cc093f03cf48ad65429889e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eeed535fdab3babeaf6447edaafbccc8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44434b647ec546fe787e2164e0be6cd2.png)
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3 . 已知
为自然对数的底数,
.
(1)求
的单调区间;
(2)证明
有且仅有两个零点;
(3)问:函数
与
的图象有几条公切线?并证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae6bf7c3198cdd4dafc81e3992f34bd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f184f195e983df4014e6c57a2e7ee67.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/575df2758d348d7d5b889fb5ad8ddafe.png)
(2)证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/575df2758d348d7d5b889fb5ad8ddafe.png)
(3)问:函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1938c093dd2fbcb752d0eb7a18d143b2.png)
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