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Trig derivative

  1. Oct 31, 2009 #1
    1. The problem statement, all variables and given/known data

    Find the first derivative of the function [tex]y=cos[(8t-7)^{\frac{-6}{7}}][/tex]



    3. The attempt at a solution
    Here is my answer:
    [tex]\frac{dy}{dx}=\frac{48sin[(8t-7)^{\frac{-6}{7}}]}{7(8t-7)^{\frac{13}{7}}}[/tex]

    How can I simplify this further?
     
  2. jcsd
  3. Oct 31, 2009 #2

    Dick

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    You can't simplify it in any significant way. Just leave it as it is.
     
  4. Oct 31, 2009 #3
    Well the thing is, I'm using a program called MathXL, and when I try to submit this answer, it rejects it.
     
  5. Oct 31, 2009 #4
    So you think the program is just malfunctioning? I doubt this because a friend of mine had the same problem as well.
     
  6. Nov 1, 2009 #5

    Dick

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    I know your answer is correct, even if the machine doesn't.
     
  7. Nov 1, 2009 #6
    The answer is correct, but it looks like they wanted all the exponents to be positive. I put this in, and got it right.

    [tex]\frac{dy}{dx}=\frac{48sin[\frac{1}{(8t-7)^{\frac{6}{7}}}]}{7(8t-7)^{\frac{13}{7}}}[/tex]
     
  8. Nov 1, 2009 #7

    Dick

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    Good job. Shows you the limitations of the program. I really wish good answers weren't subjected to this hoop jumping.
     
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