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What's Wrong With My Answer?

  1. Dec 1, 2008 #1
    1. The problem statement, all variables and given/known data

    y = (3x)^x

    (find y' )

    2. Relevant equations

    y = a^x
    y' = (a^x)(ln(a))

    and the chain rule

    3. The attempt at a solution

    3((3x)^x)(ln(3x))
     
  2. jcsd
  3. Dec 1, 2008 #2

    rock.freak667

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    Homework Helper

    Take ln of both sides of the equation

    lny=x*ln(3x)

    Now use implicit differentiation
     
  4. Dec 1, 2008 #3
    yes, that was the answer that was provided; but I don't understand why my answer is incorrect, given the fact that the derivative of a^x is (a^x)(lin(a)) and the formula seems to be of that form.
     
  5. Dec 1, 2008 #4

    rock.freak667

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    I believe for that equation to work 'a' must be a constant.
     
  6. Dec 1, 2008 #5
    O, thanks.
     
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