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Homework Help: System of linear equations

  1. May 9, 2012 #1
    Find all solutions to the following system of linear equations:
    (x1) – 2(x2) – (x3)+(x4)=1
    2(x1) – 3(x2) + (x3) – (x4)=6
    3(x1) – 3(x2) + 6(x3))=15
    (x1) + 5(x3)+(x4)=9

    Using a system of linear equations, I found:
    1 -2 -1 0 1
    0 1 3 -3 4
    0 0 0 6 0
    0 0 0 0 0

    so three solutions are:
    (x1)=9, (x2)=4, (x3)=0, (x4)=0
    (x1)=4, (x2)=1, (x3)=1, (x4)=0
    (x1)=-1, (x2)=-2, (x3)=2, (x4)=0

    How do I write my final solution (ie:what form)?
  2. jcsd
  3. May 9, 2012 #2


    Staff: Mentor

    Every solution is a point on a line that goes through <9, 4, 0, 0>. Your book should have some examples of representing lines with a parameter.

    I would advise finishing your row reduction to get the matrix in reduced row-echelon form.
  4. May 9, 2012 #3


    User Avatar
    Gold Member

    Express it into its nullspace (all the special solutions) and particular solution, if you've done that in linear algebra? The sum of the nullspace and particular solution gives the complete solution.
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