Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Matrix Question

  1. Feb 15, 2006 #1
    I have to use the Gauss-Jordan elimination to find the vector equation of the following in the format r=(a,b,c)+t(x,y,z)

    Matrix: row1=[6 8 -3|9]
    row2=[10-2-5|15]

    I got a wrong answer so can you help me solve for the vector equation please I have this answer r=(0,0,1/2)+t(1, 0,3/2)

    or x=t
    y=0
    z=1/2t+3/2
     
  2. jcsd
  3. Feb 15, 2006 #2

    TD

    User Avatar
    Homework Helper

    So the given matrix is

    [tex]
    \left( {\begin{array}{*{20}c}
    6 & 8 & { - 3} &\vline & 9 \\
    {10} & { - 2} & { - 5} &\vline & {15} \\
    \end{array}} \right)
    [/tex]

    Could you tell us what you found after row reduction?
    Also, I think you better post questions like this in "Homework & Coursework Questions".
     
    Last edited: Feb 15, 2006
  4. Feb 15, 2006 #3
    Well yeah i got row1 [0 -46 0|0]
    row2 [230 0 -115|345]
     
  5. Feb 15, 2006 #4

    TD

    User Avatar
    Homework Helper

    Looks good, you can still simplify though.
    E.g.: [4 0 -2 0] is equivalent to [2 0 -1 0] (I divided by 2).
     
  6. Feb 16, 2006 #5
    lol then why the wrong answer........It is:

    3 planes intersect at (-253/30,106/15,154/15)
     
  7. Feb 16, 2006 #6

    TD

    User Avatar
    Homework Helper

    Where is this coming from?
    You initially said that the answer had to be "r=(0,0,1/2)+t(1, 0,3/2)" which seems more logic to me... You were almost there!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook