karyye
春芽
共回答了27个问题采纳率:92.6% 举报
我们把形如
![](https://img.yulucn.com/upload/0/d8/0d8061286fa6d2917015bfaa7bfe0724_thumb.jpg)
的函数称为幂指函数,幂指函数在求导时,可以利用对数:在函数解析式两边求对数得
![](https://img.yulucn.com/upload/f/52/f5213c6a6cfb1edffc71c3ec6aea3242_thumb.jpg)
,两边对
![](https://img.yulucn.com/upload/3/6e/36e3356042126808cf1bb68f0990be0f_thumb.jpg)
求导数,得
![](https://img.yulucn.com/upload/a/38/a387cc25b331f595c21d81bd3ca150aa_thumb.jpg)
于是
![](https://img.yulucn.com/upload/4/8a/48add1edf80e3c0e0dacb5b18799678d_thumb.jpg)
,运用此方法可以求得函数
![](https://img.yulucn.com/upload/a/35/a358c524eada3beb1c304df04e94f796_thumb.jpg)
在(1,1)处的切线方程是 _________
仿照题目给定的方法,f(x)=x,g(x)=x
所以f′(x)=1,g′(x)=1
所以,y′=(1×lnx+x•1
![](https://img.yulucn.com/upload/9/85/98556160f9e6888694ce9fb76e5325c7_thumb.jpg)
x )x
x ,
∴y′| x="1" =(1×lnx+x•1
![](https://img.yulucn.com/upload/9/85/98556160f9e6888694ce9fb76e5325c7_thumb.jpg)
x )x
x | x="1" =1,
即:函数y="x"
x (x>0)在(1,1)处的切线的斜率为1,
故切线方程为:y-1=x-1,即y=x
故答案为:y=x.
1年前
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