Multiply row 2 by –1/8: 8\Y2 @RCI!
Multiply row 2 by 6 add it to row 3, replacing it: 6#2#3 @RCIJ!
If you were performing these operations by hand, you would write the
following:
A
A
aug
The symbol
(" is equivalent to") indicates that what follows is equivalent to the
previous matrix with some row (or column) operations involved.
The resulting matrix is upper-triangular, and equivalent to the set of equations
which can now be solved, one equation at a time, by backward substitution, as
in the previous example.
Gauss-Jordan elimination using matrices
Gauss-Jordan elimination consists in continuing the row operations in the upper-
triangular matrix resulting from the forward elimination process until an identity
matrix results in place of the original A matrix. For example, for the case we
just presented, we can continue the row operations as follows:
⎛
2
4
⎜
3
2
⎜
aug
⎜
4
2
⎝
⎛
1
2
3
⎜
0
8
⎜
⎜
0
6
⎝
A
aug
⎞
⎛
6
14
1
⎟
⎜
1
3
3
⎟
⎜
⎟
⎜
1
4
4
⎠
⎝
⎞
⎛
7
1
⎟
⎜
8
24
0
⎟
⎜
⎟
⎜
13
32
0
⎠
⎝
⎛
1
2
3
⎜
0
1
1
⎜
⎜
0
0
7
⎝
X +2Y+3Z = 7,
Y+ Z = 3,
-7Z = -14,
⎞
2
3
7
⎟
2
1
3
⎟
⎟
2
1
4
⎠
2
3
7
1
1
3
6
13
32
7
⎞
⎟
3
⎟
⎟
14
⎠
⎞
⎟
⎟
⎟
⎠
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