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Homework Help: Another derivative confirmation.

  1. Sep 26, 2010 #1
    1. The problem statement, all variables and given/known data
    Find the derivative of:
    f(x)= ((x+xsinx)/(1+2tan2x))3

    3. The attempt at a solution
    I solved it and got :
    f'(x)= (3(1+2tan2x)3(x+xsinx)2(sinx+xcosx+1)-12(x+xsinx)3(2tan2x+1)2(tanxsec2x))/(1+2tan2x)6

    Can anyone confirm if this is alright?
    Also, anyone knows a webpage that has an online calculator that would confirm this kind of math problems?
  2. jcsd
  3. Sep 26, 2010 #2


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    Homework Helper

    Here's what I got in Mathematica, I'm too lazy to do the algebra to compare. See attachment. Btw, Sec(x) = 1 / Cos(x).

    Attached Files:

    • f1.jpg
      File size:
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  4. Sep 26, 2010 #3
    I'm more than lazy to do this algebra. There has to be a way of comparing answers in WolframAlpha's Mathematica.
  5. Sep 26, 2010 #4
    You also use Wolframalpha.com if you don't have Mathematica. See here.
  6. Sep 26, 2010 #5
    What I meant is that there has to be some feature in WolframAlpha to compare functions and see if they are algebraically equal. Like comparing Mathematica's answer to my derivative, to my derivative.
  7. Sep 26, 2010 #6
    Perhaps plugging in a few specific values into both and seeing what happens would suffice? Or don't be lazy :smile: The algebra doen't look that bad. :uhh:
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