Question

已知fx在x0处可导,若limh→0 h/fx0－2h－fx0＝1/6,求f′x0

Answer 1

lim﹤h→0﹥h/[f（x.-2h)-f（x.)]

=lim﹤h→0﹥-2/﹛[f（x.)-f（x.-2h)]/2h﹜

=-2/f´（x.)=1/6

所以f´（x.)=-12