# Elementary Operation 1: Interchanging two rows

Consider again the linear system of equations associated to Example1.
```	 ORIGINAL  			AFTER INTERCHANGING E1 AND E4

100 x + 10 y +     z  - N = 0		-   x -    y +     z      = 1

15  x + 15 y +  15 z  - N = 0		15  x + 15 y +  15 z  - N = 0

x + 10 y + 100 z  - N = 396		    x + 10 y + 100 z  - N = 396

-   x -    y +     z      = 1		100 x + 10 y +     z  - N = 0

```
The corresponding augmented matrices for the original (A) and the transformed system (B) are:
```
[ 100  10   1   -1   0  ]         [  -1  -1   1    0   1  ]
[                       ]         [                       ]
[  15  15   15  -1   0  ]         [  15  15   15  -1   0  ]
A := [                       ]	  B := [                       ]
[  1   10  100  -1  396 ]         [  1   10  100  -1  396 ]
[                       ]         [                       ]
[  -1  -1   1    0   1  ]         [ 100  10   1   -1   0  ]

```
Clearly "A" and "B" have rows 1 and 4 interchanged but they both contain the same information about the unknowns.