y=cos^2 x
首先係本書既例子:
=2cosx d/dx(cosx)
=2cosx(-sinx)
=-sin2x
-----------------------------------
但係exercise到
y=cos^2 x
=2cosx d/dx(cosx)
=-2sinx cosx<<<書既ans
--------------------
問題就係同樣係y=cos^2 x
點解ans會有出入
係唔係2個寫法都得???
trigonometric functions
2008-02-09 12:10 am
回答 (1)
2008-02-09 12:15 am
✔ 最佳答案
當然，兩個寫法完全相同。y=cos^2 x
=2cosx d/dx(cosx)
=2cosx(-sinx) =-2sinx cosx
=-sin2x
所以寫邊個都ｏｋ！！
收錄日期: 2021-04-25 17:30:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080208000051KK01377