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Vector Lengths

  1. Oct 30, 2009 #1
    1. The problem statement, all variables and given/known data

    For u = (−1, 2, 1) and v = (3, 3, 6) find the ratio ||v|| / ||u||

    2. Relevant equations

    || u || = (u^2 + u2^2 + ...un^2)^.5

    3. The attempt at a solution

    I found the || u || to be 6^(1/2) and || v || to be 54^(1/2)
    Therefore the ratio should be 54^(1/2) divided by 6^(1/2), which calculates to 3. It turns out the answer is incorrect. Can anyone show me where I went wrong?

    Thanks.
     
  2. jcsd
  3. Oct 30, 2009 #2

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Nowhere.
     
  4. Oct 31, 2009 #3

    Mark44

    Staff: Mentor

    I agree. The ratio is 3.

    [tex]\frac{\sqrt{54}}{\sqrt{6}}~=~\frac{3\sqrt{6}}{\sqrt{6}}=~3[/tex]
     
  5. Oct 31, 2009 #4
    Okay thanks. I'll have to tell my instructor about it.
     
  6. Oct 31, 2009 #5

    Mark44

    Staff: Mentor

    Before you do, make sure that the problem you posted here is exactly the same as in your book or wherever this problem came from.
     
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