| x | ( | 28 | − | 2 | x | ) | ( | 12 | − | 2 | x | ) | = | 192 |
| 方程左边 = | x | × | 28 | ( | 12 | − | 2 | x | ) | − | x | × | 2 | x | ( | 12 | − | 2 | x | ) |
| = | x | × | 28 | × | 12 | − | x | × | 28 | × | 2 | x | − | x | × | 2 | x | ( | 12 | − | 2 | x | ) |
| = | x | × | 336 | − | x | × | 56 | x | − | x | × | 2 | x | ( | 12 | − | 2 | x | ) |
| = | 336 | x | − | x | × | 56 | x | − | x | × | 2 | x | × | 12 | + | x | × | 2 | x |
| = | 336 | x | − | x | × | 56 | x | − | x | × | 24 | x | + | x | × | 4 | x | x |
| 336 | x | − | x | × | 56 | x | − | x | × | 24 | x | + | x | × | 4 | x | x | = | 192 |