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How do you get rref with a variable in the last column?

  1. Sep 15, 2010 #1
    I'm trying to figure out how to set up a matrix where I dont know the last value ex a+2+4=x, b+4+6=x, c+2+6=x.
    Would it be something like this?
    [1,0,0,x-6]
    [0,1,0,x-10]
    [0,0,1,x-8]
     
  2. jcsd
  3. Sep 16, 2010 #2

    HallsofIvy

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    Are you missing some parameters in your equations?
    You have "a+2+4=x, b+4+6=x, c+2+6=x" which I would just write as a+ 6= x, b+ 10= x, and c+ 8= x.

    Assuming these are equations to be solve for a, b, and c, for given x, then they are exactly the same as a= x- 6, b= x- 10, and c= x- 8 which are already solved for a, b, and c in terms of x.

    If you really want to write them in terms of the "augmented matrix", yes, it would be
    [tex]\begin{bmatrix}1 & 0 & 0 & x- 6 \\ 0 & 1 & 0 & x- 10 \\ 0 & 0 & 1 & x- 8\end{bmatrix}[/tex]
    which is already "row reduced".
     
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