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Basic differentiation question

  1. Oct 9, 2010 #1
    1. The problem statement, all variables and given/known data

    Hi can anyone tell me what is the derivative of this function.

    2. Relevant equations

    p(t) = u(X(t), t) The derivative of p with respect to t

    3. The attempt at a solution

    dp/dt = du/dX * dX/dt + 1 ?? or is it going to be du/dX * dX/dt
  2. jcsd
  3. Oct 9, 2010 #2


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    You are almost right, but you need to use some partial derivatives:

    [tex] \frac{dp}{dt} = \frac{\partial u}{\partial X} \frac{dX}{dt} + \frac{\partial u}{\partial t}.[/tex]
  4. Oct 9, 2010 #3
    thank you
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