若f″(x)存在,则函数y=ln[f(x)]的二阶导数为:()
A:(f″(x)f(x)-[f′(x)]2)/[f(x)]2
B:f″(x)/f′(x)
C:(f″(x)f(x)+[f′(x)]2)/[f(x)]2
D:ln″[f(x)]·f″(x)
出自:专业知识