1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Does ln[ln(x)] = ln(x) * ln(x)

  1. Jan 23, 2010 #1
    1. The problem statement, all variables and given/known data
    Does ln[ln(x) = ln(x) times ln(x)?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 23, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Well, no. Take x=e. ln(e)*ln(e)=1, ln(ln(e))=ln(1)=0.
  4. Jan 23, 2010 #3


    Staff: Mentor

    And generally speaking, f(f(x)) is different from f(x)*f(x). It's the difference between function composition (evaluation a function of a function) and function multiplication.
  5. Jan 24, 2010 #4


    User Avatar
    Homework Helper

    Maybe if we manipulated the expression a little it will become clearer that each function is not equal to each other.





    Does it look more obvious now as to why these expressions are not equal?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Does ln[ln(x)] = ln(x) * ln(x)
  1. Domain of 10/ln x (Replies: 5)

  2. E^-ln(x) equation (Replies: 4)