f(X)=ln(X)/X
求
1.f'(X)=
2.f''(X)=
過程
急 兩題微分
2011-09-12 3:57 am
回答 (3)
2011-09-12 4:24 am
✔ 最佳答案
f(x)=lnx/x求
1.f'(x)=
y=lnx/x
xy=lnx
xy'+y=1/x
xy'=1/x－y
xy'=1/x－lnx/x
xy'=(1－lnx)/x
y'=(1－lnx)/x^2
f'(x)=(1－lnx)/x^2
2.f''(x)=
xy'+y=1/x
xy''+y'+y'=－1/x^2
xy''=－1/x^2－2y'
xy''=－1/x^2－2(1－lnx)/x^2
xy''=(－1－2+2lnx)/x^2
y''=(－3+2lnx)/x^3
f''(x)=(－3+2lnx)/x^3
2011-09-12 4:59 am
2011-09-12 4:30 am
quotient rule !!
收錄日期: 2021-04-30 16:00:45
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110911000010KK06540