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More log questions.

  1. May 12, 2005 #1
    Can some one check my answers please?

    The answers are in my reply post at the bottom of this page THANKS :smile:


    I have a couple more log questions Im stuck on. They keep giving me log questions that they never showed me how to do.. very fustrating!
    I need to evaluate the following logarithms:

    68 a). log22^log55
    I dont even know where to begin.. I never done a log with an exponent log???

    69. log25=log2(x+32)-log2x

    Determine the derivative of:
    70 c) y= 2x^3 e^4x

    e) y= square root(x^3 + e^-x +5)
    I know this one should probably go to. (x^3 + e^-x +5)^1/2... then,
    dy/dx= (x^3 + e^-x +5)^1/2 * 1/2(x^3 + e^-x +5)^-1/2 * (3x^2)now im confused??? does the e^-x have a derivative?? like -xe^-2?? i got no idea.
    CAN ANYONE HELP ME PLEASE....
    THANKZ YA!
     
    Last edited: May 12, 2005
  2. jcsd
  3. May 12, 2005 #2
    For part a, is that

    [tex](\log_{2}2)^{\log_{5}5}[/tex] or [tex] \log_{2}(2)^{\log_{5}5}[/tex]?
     
  4. May 12, 2005 #3
    umm there are no brackets, but i think the 2 is in part with the log2
     
  5. May 12, 2005 #4

    Pyrrhus

    User Avatar
    Homework Helper

    Hrm

    [tex] \log_{5} 5 = 1 [/tex]

    [tex] 5^1 = 5 [/tex]

    [tex] log_{2} 5= log_{2} (x+32) - log_{2} x [/tex]

    [tex] log_{2} 5= log_{2} \frac{x+32}{x} [/tex]

    [tex] 5 = \frac{x+32}{x} [/tex]
     
    Last edited: May 12, 2005
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