Question 358373
{{{matrix(3,4,2, 1,1,9,-1,-1,1,1,3,-1,1,9)}}}~{{{matrix(3,4,1,1,-1,-1,2,1,1,9,3,-1,1,9)}}} Interchanging rows 1 and 2, and multiplying the new row 1 by -1.
~{{{matrix(3,4,1,1,-1,-1,0,-1,3,11,0,-4,4,12)}}}, multiply row1 by -2, and multiply row1 -3.
~{{{matrix(3,4,1,1,-1,-1,0,-1,3,11,0,0,2,8)}}}, add row2 to row3.
~{{{matrix(3,4,1,1,-1,-1,0,1,-3,-11,0,0,1,4)}}}, multiply row2 and row3 by -1.
Thus z = 4, y - 3z = -11, x+y-z = -1.
y - 3*(4) = -11, y = -11+12 = 1,
x+y-z = -1.  x+1-4 = -1, x-3=-1, x = 2.
Therefore x = 2, y = 1, and z = 4.