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Homework Help: How is this proof valid? ax(bxc) = (c.a)b-(b.a)c

  1. Sep 15, 2005 #1
    Hello everyone, i'm looking at this proof and its making sence until the very last part, and it doens't friggin' work...the terms don't match up... Also is the notation I used correct in the proof, like does there have to be any vector notation I don't have or do you see anyhting you don't like? I'm proving the "The Vector triple product"
    Here is my proof:
    http://img89.imageshack.us/img89/9758/rpooof6rk.jpg [Broken]
    Look at the 2nd part of ax(bxc) -----> a1b1c3 - a2b22c3 + a2b3c2
    then look at the last part (c.ad)b - (b.a)c ---> a1b3c1 - a1b1c3 + a2b3c2 - a2b2c3

    You see only 1 term isn't match up!! the a1b1c3 not equal to a1b3c1 whats going on? Thanks
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Sep 15, 2005 #2
    Nevermind, my friend found the problem! I forgot a term in ax(bxc) part.
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