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Homework Help: Rules for differentiation

  1. Mar 10, 2014 #1
    Problem statement
    Find dy/dx
    ImageUploadedByPhysics Forums1394493023.920751.jpg

    Revelant equations

    Attempt at a solution
    ImageUploadedByPhysics Forums1394493079.089215.jpg

    This is what I got to so far but now I'm stuck... Any hints?
  2. jcsd
  3. Mar 10, 2014 #2


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    Do you think you can use the template from now on ?
    You need at least one relevant equation, and it is not clear to me what you do in your aattempt. Could you elaborate ?
  4. Mar 10, 2014 #3


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    It would be less confusing if you wrote y using exponents before doing the differentiation. Check the derivative of the second part of your expression; I think you have an error in the sign.
  5. Mar 10, 2014 #4

    Yes I think I put a negative 1/2 should be a positive
  6. Mar 10, 2014 #5

    Ok I am not sure what equation to use in this though.
  7. Mar 10, 2014 #6


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    You are making a fundamental mistake: the derivative of 1/y is NOT 1 over the derivative of y. Either use the quotient rule to differentiate [itex]\frac{1}{\sqrt{x}}[/itex] or write the whole function as [itex]2x^{1/2}+ x^{-1/2}[/itex] and use the derivative rule [itex](x^n)'= nx^{n-1}[/itex].
    Last edited by a moderator: Mar 10, 2014
  8. Mar 10, 2014 #7

    Thank you I understand it now
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