题目

已知函数f(x)满足f(x3-1)=,求f′(x). 答案：思路分析一:欲求f′(x),需先求f(x),用换元法求解.解法一:令t=x3-1,则x=.∴f(x)=.∴f′(x)=.思路分析二:依据复合函数的求导法则进行求解.解法二:y=f(x3-1)可看成是由y=f(t),t=x3-1复合而成的.对原式两边求导,得f′(t)·(x3-1)′=.∴f′(t)=.把x=代入该表达式,可得f′(t)=,即f′(x)=. I need one more stamp before my collection ______.A．had completed 　B．completesC．has been completedD．is completed