先计算取对数后的极限 lim(n→∞)[lnf(x0+1/n)-lnf(x0)]/(1/n) = f'(x0)/f(x0),所以 lim(n→∞)[f(x0+1/n)/f(x0)]^n = e^lim(n→∞)[lnf(x0+1/n)-lnf(x0)]/(1/n) = e^[f'(x0)/f(x0)]....
