Question 102522
Start with the given matrix:



{{{(matrix(3,4,1,1,-1,2,2,3,-1,7,3,-2,1,9))}}}
 Add  -2*Row 1 to Row 2 to get the new Row 2


{{{(matrix(3,4,1,1,-1,2,0,1,1,3,3,-2,1,9))}}}


 Add  -3*Row 1 to Row 3 to get the new Row 3


{{{(matrix(3,4,1,1,-1,2,0,1,1,3,0,-5,4,3))}}}


 Add  5*Row 2 to Row 3 to get the new Row 3


{{{(matrix(3,4,1,1,-1,2,0,1,1,3,0,0,9,18))}}}


Multiply Row 3 by {{{1/9}}} to make the pivot 1:


{{{(matrix(3,4,1,1,-1,2,0,1,1,3,0,0,1,2))}}}



 Add  -1*Row 3 to Row 2 to get the new Row 2


{{{(matrix(3,4,1,1,0,4,0,1,0,1,0,0,1,2))}}}



Add  -1*Row 2 to Row 1 to get the new Row  


{{{(matrix(3,4,1,0,0,3,0,1,0,1,0,0,1,2))}}}



The matrix is now in <font size=4><b>reduced row echelon form</b></font>



If you need more help with row reduction or Gaussian elimination, check out <a href=http://www.math.odu.edu/~bogacki/lat/> The Linear Algebra Toolkit</a>, and it will take you step-by-step through any Gaussian elimination problem.