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Question on form of differential

  1. Sep 30, 2005 #1
    My book says:

    let p stand for partial, u is a function

    p(uAx) / px = pu(Ax)/px + up(Ax)/px

    How can it be valid?
  2. jcsd
  3. Sep 30, 2005 #2
    First of all, what is u a function of? Second, did you mean A(x)?
  4. Sep 30, 2005 #3
    u is just say xyz and Ax means A subscript x
  5. Sep 30, 2005 #4


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    It would help us all if you would take a few minutes to read through this thread . LaTex is really very easy and it makes it much easier to present problems such as yours.
  6. Sep 30, 2005 #5
    [tex]\frac{\partial }{\partial x}\left( uA_{x} \right)\; =\; \frac{\partial u}{\partial x}\left( A_{x} \right)+u\frac{\partial A_{x}}{\partial x}[/tex]

    To me, the right hand of the equation is saying the left hand twice rather than reworking it.
  7. Sep 30, 2005 #6
    That's just the straight-up definition of the chain rule.
  8. Oct 1, 2005 #7
    Thanks! :)
    Last edited: Oct 1, 2005
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