| 1 -1 1 |
|D|= | 1 0 -1 |=1+1+1=3
| 0 1 1 |
| 2 -1 1 |
|D1|= | 0 0 -1 |=-1+2=1
| -1 1 1 |
| 1 2 1 |
|D2|= | 1 0 -1 |=-1-1-2=-4
| 0 -1 1 |
| 1 -1 2 |
|D3|= | 1 0 0 |=2-1=1
| 0 1 -1 |
x1=|D1|/|D|=1/3
x2=|D2|/|D|=-4/3
x3=|D3|/|D|=1/3