| xy |
| x+y |
| xz |
| x+z |
| yz |
| y+z |
∴
| 1 |
| x |
| 1 |
| y |
| 1 |
| 2 |
| 1 |
| x |
| 1 |
| z |
| 1 |
| 3 |
| 1 |
| y |
| 1 |
| z |
| 1 |
| 4 |
解得：
| 1 |
| x |
| 7 |
| 24 |
| 1 |
| y |
| 5 |
| 24 |
| 1 |
| z |
| 1 |
| 24 |
∴x=
| 24 |
| 7 |
| 24 |
| 5 |
∴原式=7×
| 24 |
| 7 |
| 24 |
| 5 |
=24+24-48
=0．
| xy |
| x+y |
| xz |
| x+z |
| yz |
| y+z |
| xy |
| x+y |
| xz |
| x+z |
| yz |
| y+z |
| 1 |
| x |
| 1 |
| y |
| 1 |
| 2 |
| 1 |
| x |
| 1 |
| z |
| 1 |
| 3 |
| 1 |
| y |
| 1 |
| z |
| 1 |
| 4 |
| 1 |
| x |
| 7 |
| 24 |
| 1 |
| y |
| 5 |
| 24 |
| 1 |
| z |
| 1 |
| 24 |
| 24 |
| 7 |
| 24 |
| 5 |
| 24 |
| 7 |
| 24 |
| 5 |