若函数f(x)在x=a处的导数为A,求limh趋向于0f(a+4h)-f(a+5h)/h的值

f'(x) = lim(h->0) [f(x+h) -f(x) ] /hf'(a) =lim(h->0) [f(a+h) -f(a) ] /hlim(h->0) [f(a+4h) -f(a+5h)] /h=lim(h->0) [ (f(a+4h) -f(a)) - ( f(a+5h)-f(a)) ] /h= lim(h->0) [f(a+4h)-f(a)] /h - lim(h->0) [f(a+...