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Homework Help: Total differentials

  1. Sep 6, 2008 #1
    total differentials!!

    a.) f = 1/(x+y2)

    b.) f = ln(x2y)

    c.) P = [(RT)/(V-B)]-[A/(T1/2V2)]

    what are the total differentials of these functions?
     
  2. jcsd
  3. Sep 6, 2008 #2

    cristo

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    Re: total differentials!!

    You need to show some work before we can help you. E.g. what is the definition of a total differential? What have you tried for each question?
     
  4. Sep 6, 2008 #3
    Re: total differentials!!

    so far these are the answers I have come up with...

    A. [-1/((x+y2)2)]dx - [2y/((x+y2)2)]dy
    I started this problem by moving the denominator up but i am not sure that was the correct first move.

    b. (2xy/x2y)dx + (x2/x2y)dy

    c. I was not sure where to start with this problem.
     
  5. Sep 6, 2008 #4

    cristo

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    Re: total differentials!!

    First two are correct. For the third, just do the same thing you've done in the first two, but this time the expression will have 5 terms.
     
  6. Sep 6, 2008 #5
    Re: total differentials!!

    for part C I assumed that A,B, and R are constants and the answer I came up with is..

    [-RT(V-B)-2-AT-1/2*-2V-3)+(R/(V-B)+1/2AT-1.5V-2]
     
  7. Sep 6, 2008 #6

    Dick

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    Re: total differentials!!

    Shouldn't there be a dT and a dV in there, as there were dx and dy in the other cases?
     
  8. Sep 6, 2008 #7
    Re: total differentials!!

    Woops. I forgot to put those in. Thanks!
     
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