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Homework Help: Matrix help!

  1. Oct 27, 2005 #1
    I've been asked to solve the following matrix and find the solutions but I'm not sure if I've reached the correct 'end' matrix.

    Original matrix:

    1 2 -1 3
    -1 3 4 10
    -1 1 -2 8

    The last matrix I got after my calculations:

    1 2 -1 3
    0 1 1 11/3
    0 0 8 26/3


    Thanks for reading
  2. jcsd
  3. Oct 27, 2005 #2


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    Science Advisor

    What do you mean by "solving" a matrix? I know how to solve equations and I know, more generally, how to solve problems but I don't know what is meant by solving a matrix.
    You appear to be row-reducing a matrix to row-echelon form. If so that is certainly not what I get. How about stating exactly what the problem is and showing your work?
  4. Oct 27, 2005 #3
    oh its okay, I've managed to work out where I went wrong. Sorry for not stating the problem clearly :uhh:

    Erm but I have two more questions to ask, and was wondering if anyone can offer me some help or hints. I havent got any working for this because I really do not have any idea how to approach the answer.

    Can anyone explain to me what a subspace is? I've got notes on it but I'm confused with all the notation etc. Thanks in advance!

    Last edited by a moderator: Apr 21, 2017
  5. Oct 27, 2005 #4
    A subspace of a vector space is just a subset of the vectors in the space that are also a vector space. For example, R2 is a 2-dimensional vector space. The set of vectors (x,y) that satisfy the equation y=x is a subspace of R2 but the set of vectors (x,y) that satisfy x2 + y2 = 1 is not.
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