=
=[]
=[+]
=[f′(x0)+f′(x0)]=f′(x0).
4.函数y=在x=1处的导数为______________.
答案:
解析:Δy=-1,=
,y′|x=1=
5.已知函数f(x)在x=a处可导,则
(1)=_________________.
(2)=___________________.
答案:(1)2f′(a) (2)0
解析:(1)原式
=+
=f′(a)+f′(a)=2f′(a).
(2)原式=·h
=·
=f′(a)·0=0.
6.利用导数的定义求下列函数的导数.