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=_______?
答
f(x)'
答
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)
答
lim f(x1-h)-f(x1)/-h
=lim-[f(x1)-f(x1-h)]/(-h);
=lim[f(x1)-f(x1-h)]/h
=f'(x1).