| 5 0 4 2 |-2× |1 1 1 1 |
| 1 -1 2 1 |-| |1 1 1 1 |
4 1 2 0 |
|1 1 1 1 | =
| 3 -2 2 0 |
| 0 -2 1 0 |
|4 1 2 0 |
|1 1 1 1 | =
| 3 -2 2 |
| 0 -2 1 |
|4 1 2 | =-15+8=-7