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Homework Help: Property of exponential functions

  1. Oct 22, 2011 #1
    1. The problem statement, all variables and given/known data

    Working on some Laplace transforms, and my lack of knowledge of some properties of exponential functions is coming back to bite me(again). I'm stuck trying to figure out if:

    e^(-pi*s) - e^(-2pi*s) = e^(-pi*s - (-2pi*s))

    Is a true statement or not. I've searched around the internet trying to find properties of adding/subtracting exponential functions, but I couldn't find anything.
  2. jcsd
  3. Oct 22, 2011 #2
    You can turn the second term into [tex]e^{-\pi s}/e^{-2\pi s}[/tex]
    from there multiply both sides by this denominator. This will reduce both the left and right side to one term. Do they equal?
  4. Oct 23, 2011 #3
    This statement is not true. This only applies to multiplication of exponents.


    Refer to this for exponential properties: http://www.efunda.com/math/exp_log/exp_relation.cfm

    @Sandy: You are wrong as well. Your equation does not equal to the original problem
    Last edited: Oct 23, 2011
  5. Oct 23, 2011 #4


    Staff: Mentor

    To answer your question, no, the left side is not equal to the right side.
  6. Oct 23, 2011 #5


    User Avatar
    Homework Helper

    He's not wrong, you just missed the part about him saying "the second term". But I find that advice to be quite useless if it still takes knowledge about exponential properties to determine the correct answer.
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