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Homework Help: Integral Problem

  1. Nov 25, 2013 #1
    1. The problem statement, all variables and given/known data
    d2y/dx2 = 7sec^2(pix/4)tan(pix/4)

    2. Relevant equations

    3. The attempt at a solution

    dy/dx = 14/pi sec^2(pix/4)-28/pi
    y = 56tan(pix/4)/pi^2-28x/pi+5-56/pi^2+28/pi

    Not sure where I went wrong, but I checked on my calc and it wasn't equal.
  2. jcsd
  3. Nov 25, 2013 #2
    The first derative should be something with tan^2(..).
  4. Nov 25, 2013 #3
    1 + tan^2(...) = sec^2(...) but 1 is just part of c


    dy/dx = 14/pi tan^2(pix/4) - 14/pi

    y = 56tan(pix/4)/pi^2 - 56(pix/4)/pi^2 - 14x/pi + 5 - 56/pi^2 + 28/pi

    could anyone check this please?
    Last edited: Nov 25, 2013
  5. Nov 25, 2013 #4


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    Science Advisor
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    Looks right, but you can simplify a little. Two terms are the same.
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