Thread: ln function...finding value of f'(x)
View Single Post
  #2  
Old December 6th, 2007, 09:48 PM
Soroban Soroban is offline
Super Member

  
Join Date: May 2006
Location: Lexington, MA (USA)
Posts: 7,286
Thanks: 555
Thanked 4,649 Times in 3,712 Posts
Soroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond reputeSoroban has a reputation beyond repute
Default
Hello, polymerase!

Quote:
If f(x)\:=\:\ln(\ln x), find the value of f'\left(\frac{1}{e}\right)

Choices: .a)\;\text{-}\frac{1}{e}\qquad b)\;\text{unde{f}ined}\qquad c)\;\frac{1}{e}\qquad d) \;2e \qquad e) \;\sqrt{e}

I agree with your answer . . . {\color{blue}\text{b) unde{f}ined}}

f\left(\frac{1}{e}\right) \:=\:\ln\left[\ln\left(\frac{1}{e}\right)\right] \;=\;\ln\left[\ln\left(e^{-1}\right)\right] \;=\;\ln(-1) .??

The function does not exist at that point, so neither does its derivative.
Reply With Quote