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Homework Help: Computing parallel vectors

  1. Jul 14, 2012 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    3. The attempt at a solution

    I can't get the answer above. Is u -4 over 15? if so, the dot product of u and x should be
    -20 + 105. I'm clearly on the wrong track.
  2. jcsd
  3. Jul 14, 2012 #2
    If you're going to do it that way, notice that the 1/5 term in the unit vector u should be multiplied by both -4 and 3 before it is dotted with x.
  4. Jul 14, 2012 #3
    Thanks, I was able to figure it out by looking at the next example.
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