| 2 | ( | 12 | − | 3 | x | ) | ( | 9 | − | 2 | x | ) | = | 45 |
| 方程左边 = | 2 | × | 12 | ( | 9 | − | 2 | x | ) | − | 2 | × | 3 | x | ( | 9 | − | 2 | x | ) |
| = | 24 | ( | 9 | − | 2 | x | ) | − | 6 | x | ( | 9 | − | 2 | x | ) |
| = | 24 | × | 9 | − | 24 | × | 2 | x | − | 6 | x | ( | 9 | − | 2 | x | ) |
| = | 216 | − | 48 | x | − | 6 | x | ( | 9 | − | 2 | x | ) |
| = | 216 | − | 48 | x | − | 6 | x | × | 9 | + | 6 | x | × | 2 | x |
| = | 216 | − | 48 | x | − | 54 | x | + | 12 | x | x |
| = | 216 | − | 102 | x | + | 12 | x | x |
| 216 | − | 102 | x | + | 12 | x | x | = | 45 |