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I Multi variable differential

  1. Aug 12, 2016 #1
    Hi

    9785505_1470928696.jpg

    I understood above differential

    ## typo. RHS= 2*f ' (x,2z-x)

    but, what is answer of below equation?

    5514124_1470928737.jpg

    is this right?

    f ' ( g(z),2z-x) * g' (z) + f ' ( g(z),2z-x) *2
     
  2. jcsd
  3. Aug 12, 2016 #2

    Krylov

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    This notation is ambiguous, because it is not clear whether you differentiate ##f## w.r.t. the first or second variable. So I would write
    $$
    \frac{d}{dz} f(x, 2z - x) = 2 D_2f(x, 2z - x)
    $$
    instead. (There are other notations, but choose one that is clear.)
    Same comment as above. Change the first ##f'## to ##D_1f## and the second ##f'## to ##D_2f##.
     
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