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Homework Help: Simple derivative problem

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data
    ln (2x^2 + 3)


    2. Relevant equations
    ln 2x^2 + ln 3


    3. The attempt at a solution
    (4x/2x^2) + (3/3)
    (2x/x^2) + 1

    I know this is a simple problem but what is the derivative of ln3? Is it 1 (3/3) or 0?
     
  2. jcsd
  3. Sep 30, 2007 #2
    properties of logs

    [tex]\ln(ab)=\ln(a)+\ln(b)[/tex]

    what you have is

    [tex]\ln(a+b)=\ln(a+b)[/tex]

    example

    [tex]\ln(x^{2}+3)[/tex]

    differentiating

    [tex]\frac{2x}{x^{2}+3}[/tex]
     
    Last edited: Sep 30, 2007
  4. Sep 30, 2007 #3
    Can't you distribute the ln to get lna + lnb? I don't know what the derivative of ln3 is? Is it 3/3 or 0/3.
     
  5. Sep 30, 2007 #4
    i just updated my post, i clicked submit on accident while trying to preview.
     
  6. Sep 30, 2007 #5
    Oh okay I see now. So it would be...
    (4x)/(2x^2 + 3)
    (2x)/(x^2 + 3)
     
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