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!

Diffrentiation of natural logs (ln)

  1. Sep 14, 2010 #1
    the question is: differentiate wiith repsect to x:


    i differentiated and got :



    I dont think this is correct. The answer should be ln5/5.

    Can anyone help me?

  2. jcsd
  3. Sep 14, 2010 #2
    That's not right. The answer shouldn't be ln5/5, because that's a number. The answer should be a function.

    Use the chain rule: power to the front, subtract 1, multiply by the derivative of what's inside the bracket.
  4. Sep 14, 2010 #3
    So the answer would be;

    y'=1/5 (5)(ln5x)^(1/5-1)

    y'= (ln5x)^-4/5

    is this right??

    Thanks for helping :)
  5. Sep 14, 2010 #4
    Almost. The derivative of ln(f(x)) is f'(x)/f(x), so the derivative of ln(5x) is 5/(5x) = 1/x.

    So replacing (5) with (1/x), then simplifying is the correct answer.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Diffrentiation of natural logs (ln)
  1. Natural logs (Replies: 7)

  2. Natural Log (Replies: 4)