| ( | - | 7 | − | x | ) | ( | 13 | − | x | ) | + | 4 | × | 24 | = | 0 |
| 方程左边 = | ( | - | 7 | − | x | ) | ( | 13 | − | x | ) | + | 96 |
| ( | - | 7 | − | x | ) | ( | 13 | − | x | ) | + | 96 | = | 0 |
| 方程左边 = | - | 7 | ( | 13 | − | x | ) | − | x | ( | 13 | − | x | ) | + | 96 |
| = | - | 7 | × | 13 | + | 7 | x | − | x | ( | 13 | − | x | ) | + | 96 |
| = | - | 91 | + | 7 | x | − | x | ( | 13 | − | x | ) | + | 96 |
| = | 5 | + | 7 | x | − | x | ( | 13 | − | x | ) |
| = | 5 | + | 7 | x | − | x | × | 13 | + | x | x |
| = | 5 | − | 6 | x | + | x | x |
| 5 | − | 6 | x | + | x | x | = | 0 |