| ( | - | 4 | − | 3 | d | + | 2 | d | ) | ( | - | 4 | − | 3 | d | + | 4 | d | ) | = | 7 |
| 方程左边 = | - | 4 | ( | - | 4 | − | 3 | d | + | 4 | d | ) | − | 3 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) | + | 2 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) |
| = | 4 | × | 4 | + | 4 | × | 3 | d | − | 4 | × | 4 | d | − | 3 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) | + | 2 |
| = | 16 | + | 12 | d | − | 16 | d | − | 3 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) | + | 2 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) |
| = | 16 | − | 4 | d | − | 3 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) | + | 2 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) |
| = | 16 | − | 4 | d | + | 3 | d | × | 4 | + | 3 | d | × | 3 | d | − | 3 | d |
| = | 16 | − | 4 | d | + | 12 | d | + | 9 | d | d | − | 12 | d | d | + | 2 |
| = | 16 | + | 8 | d | + | 9 | d | d | − | 12 | d | d | + | 2 | d | ( | - | 4 | − | 3 | d | + | 4 | d | ) |
| = | 16 | + | 8 | d | + | 9 | d | d | − | 12 | d | d | − | 2 | d | × | 4 |
| = | 16 | + | 8 | d | + | 9 | d | d | − | 12 | d | d | − | 8 | d | − | 6 |
| = | 16 | + | 0 | d | + | 9 | d | d | − | 12 | d | d | − | 6 | d | d |
| 16 | + | 9 | d | d | − | 12 | d | d | − | 6 | d | d | + | 8 | d | = | 7 |