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Derivative of Natural log

  1. Nov 30, 2006 #1
    Having some trouble understanding derivatives including numbers to the "X" power. For example, f(x)= 7^8^x, f'(x)=?
    help please!
     
  2. jcsd
  3. Nov 30, 2006 #2

    arildno

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    Are you talking of:
    a) [itex]f(x)=(7^{8})^{x}[/itex]
    b) [itex]f(x)=7^{8^x}[/itex]
     
  4. Nov 30, 2006 #3

    radou

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    You should find this link useful: http://math2.org/math/derivatives/more/b^x.htm.
     
  5. Nov 30, 2006 #4
    i'm working on the B) one
     
  6. Nov 30, 2006 #5

    arildno

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    So, set [tex]u(x)=8^{x}[/tex], and use the chain rule of differentiation.
     
  7. Nov 30, 2006 #6
    ok, thanks, what about dividing them? do i still use rules of differentiation. for example, 3^x/4^x
     
  8. Nov 30, 2006 #7

    arildno

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    Or, use first:
    [tex]\frac{3^{x}}{4^{x}}=(\frac{3}{4})^{x}[/tex]
     
  9. Nov 30, 2006 #8
    thanks so much!
     
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