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Clarification on Partial Derivative Symbols

  1. Aug 26, 2010 #1
    1. The problem statement, all variables and given/known data

    See uploaded image.

    2. Relevant equations

    n/a

    3. The attempt at a solution

    I’ve never seen this format so I am not sure what it is asking. Taking L1.B as an example. They are partials, but does it mean partial of x with respect to z? And then partial of y with respect to z? I am pretty sure that part is right after looking at it again.

    The one I am really confused about it L1.3D. There are two partial symbols with y and z in front of w. Maybe partial of x then y with respect to w?

    And I guess the same thing with C. Partial of c1? Since c is a constant wouldn’t that be zero every time? There is no x with the partial symbols, so I don't think I do anything with the x or y?

    I have only seen the following when referring to partial derivatives...

    [tex]\frac{\partial x}{\partial y}[/tex]
    (partial of x with respect to y)

    And...

    [tex]F_{x}[/tex]
    (partial of x)
     

    Attached Files:

  2. jcsd
  3. Aug 26, 2010 #2

    lanedance

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    read it as follows:
    [tex]\partial_x = \frac{\partial }{\partial x}[/tex]
     
  4. Aug 26, 2010 #3
    When in doubt, search Google/Wiki ;)! http://en.wikipedia.org/wiki/Partial_derivative

    3B. partial of z with respect to x...and partial of z with respect to y.
    3C. I'm not sure on this one. I guess partial of u w/ respect to c1, c2, c3, separately.
    3D. partial of w with respect to y and then partial with respect to x.
     
  5. Aug 27, 2010 #4
    Perfect, that is what I was thinking. Thanks for the responses.

    Back to the c1, c2, c3... since those are constants, isn't that just going to be zero? Or am I missing something still?
     
  6. Aug 27, 2010 #5

    Dick

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    Why do you think c1, c2 and c3 are constants? If you are taking partial derivatives of them, you shouldn't be thinking of them as constants.
     
  7. Aug 27, 2010 #6
    Just assume x is not a function of c1, c2, or c3, and go from there.
     
  8. Aug 27, 2010 #7
    Got it. I guess I am used to c being used as a constant. Plus we just did separation of variables where c1 and c2 where used as constants. With that and the fact that they were before the variables, like most constants, I just assumed that's why they were.

    No matter how much I do these, I always get thrown off when different variables get used. :rofl:
     
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