| ( | X | X | − | 6 | ) | ( | X | X | − | 6 | ) | − | 6 | = | 0 |
| 方程左边 = | X | X | ( | X | X | − | 6 | ) | − | 6 | ( | X | X | − | 6 | ) | − | 6 |
| = | X | X | X | X | − | X | X | × | 6 | − | 6 | ( | X | X | − | 6 | ) | − | 6 |
| = | X | X | X | X | − | X | X | × | 6 | − | 6 | X | X | + | 6 | × | 6 |
| = | X | X | X | X | − | X | X | × | 6 | − | 6 | X | X | + | 36 | − | 6 |
| = | X | X | X | X | − | X | X | × | 6 | − | 6 | X | X | + | 30 |
| X | X | X | X | − | X | X | × | 6 | − | 6 | X | X | + | 30 | = | 0 |