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Homework Help: Easy Ratio Vector Question, but not sure if answer is wrong

  1. Jun 5, 2012 #1
    1. The problem statement, all variables and given/known data
    Let A, B be points in R3 with position vectors


    Let Q be the point on AB such that AQ= 2/3 AB
    Find q, the position vector of Q

    2. Relevant equations
    The back of the book says the answer is: (2,-3,-1)

    3. The attempt at a solution
    First, I found the vector of AB: (-6,-3,-3)
    So Q should be: a+(2/3)(AB)
    ie: (7,-2,3)+(-4,-2,-2)
    Which is different to the answer given by the book.
    Did i do anything wrong?
  2. jcsd
  3. Jun 5, 2012 #2
    What you have done is right
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