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!

Homework Help: Log Rules

  1. May 1, 2014 #1
    1. The problem statement, all variables and given/known data

    Got to part of a problem where I have exp(-3ln(x)) and I am confused as to whether the next step is:

    a) exp(ln(x^-3)) = x^-3


    b) exp(-ln(x^3)) = -x^3

    I think the correct step is (a) but not certain, any help would be great :)
  2. jcsd
  3. May 1, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Yes (a) is the correct result.

    For (b):

    exp(-ln(x^3)) = ##\displaystyle \frac{1}{e^{\ln (x^3)}}\ ## → ##\displaystyle \ \frac{1}{x^3} \ .##
  4. May 2, 2014 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Here it appears you're saying ##e^{-a} = -e^a##, that you can simply pull the minus sign out front, which you probably know isn't correct.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Threads for Rules
Bayes' Rule question