| 12 | ( | x | − | 1 | ) | ( | - | 5 | ) | = | 0 |
| 方程左边 = | 12 | x | ( | - | 5 | ) | − | 12 | × | 1 | ( | - | 5 | ) |
| = | 12 | x | ( | - | 5 | ) | − | 12 | ( | - | 5 | ) |
| = | - | 12 | x | × | 5 | − | 12 | ( | - | 5 | ) |
| = | - | 60 | x | − | 12 | ( | - | 5 | ) |
| = | - | 60 | x | + | 12 | × | 5 |
| = | - | 60 | x | + | 60 |
| - | 60 | x | + | 60 | = | 0 |
| - | 60 | x | = | 0 | − | 60 |
| - | 60 | x | = | - | 60 |
| 60 | = | 60 | x |
| 60 | x | = | 60 |
| x | = | 60 | ÷ | 60 |
| = | 60 | × | 1 60 |
| = | 1 | × | 1 |
| x | = | 1 |