设函数f(x)在x1处可导,则h→0 lim f(x1-h)-f(x1)/-h=_______?

问题描述:

设函数f(x)在x1处可导,则
h→0 lim f(x1-h)-f(x1)/-h=_______?

f(x)'

把-h看作自变量x在x=x1处的增量,此极限即为函数f(x)在x=x1处导数的定义,所以结果是f'(x1)

lim f(x1-h)-f(x1)/-h
=lim-[f(x1)-f(x1-h)]/(-h);
=lim[f(x1)-f(x1-h)]/h
=f'(x1).