So [1] is true only for f(x) and g(x) not constant?
Thanks
更新1:
You are right, i am thinking about derivatives, sorry
You are right, i am thinking about derivatives, sorry
收錄日期: 2021-05-01 15:19:48
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150711115531AAz5qur