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Homework Help: Nth derivatives

  1. Aug 28, 2013 #1
    1. The problem statement, all variables and given/known data

    how to find nth derivatives cos^12x and a-x/a+x

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Aug 28, 2013 #2
    help please..
  4. Aug 28, 2013 #3
    Don't panic. Since you know derivation is quite easy to deduce them. Write the first two or three derivatives and see the pattern. I 'll give an example to understand:
    (sinx)' = cosx = sin(x+pi/2)
    (sinx)'' = (cosx)' = -sinx= sin(x+pi), (sinx)''' = -cosx = sin(x+3pi/2), (sinx)(4) = sinx = sin(x+2pi).
    SO the n-nth derivative of sinx is sin(x + n*pi/2)
    Yours are all the same way.
  5. Aug 28, 2013 #4


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    Homework Helper

    hi makar! welcome to pf! :wink:

    try it, and show us what you get :smile:

    start with the first few derivatives of cos12x

    (you may spot a pattern)
  6. Aug 28, 2013 #5


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    Homework Helper

  7. Aug 30, 2013 #6
    thank u everyone for helping me..
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