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Log(-2)-8 = 3

  1. Sep 15, 2013 #1
    I know that in logarithms we can not set as base a negative number,but look at this(in the brackets I will put the base.): log(-2)-8=3 Mathematics say that is wrong,but why?
    If we tell -2^3=-8 we have a correct result.
    So??? Thank you!!!
     
  2. jcsd
  3. Sep 15, 2013 #2

    arildno

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    That is certainly true.

    But:
    You'll only be able to find such matches for some INTEGER values.

    With any positive number distinct from 1 as chosen as base, we can, with the associated logarithm function represent EVERY positive number as a power of our base.

    Having a negative number as your base, however, you cannot gain this type of general usage, that is, a continuous logarithm function covering, say, all the negative numbers is impossible to construct.
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    Thus, for simplicity, we say that you can't have a negative number as your base.
     
  4. Sep 15, 2013 #3
    That was very clear answer. I hope to be many other guys like you in this forum
     
  5. Sep 15, 2013 #4

    arildno

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    You are welcome! There are many such guys here. :smile:
     
    Last edited: Sep 15, 2013
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