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Expanding partial derivatives

  1. Jan 28, 2012 #1
    In this textbook, how exactly are 2.2.19 and 2.3.21 equal?

    http://i.imgur.com/LrcXE.png
     
  2. jcsd
  3. Jan 28, 2012 #2

    tiny-tim

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    Science Advisor
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    hi crocomut! :smile:

    standard trick:

    swap i and j … since they're both dummy indices, that gives you the same expression!

    then add, and divide by 2 :wink:
     
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