| 3 | ( | x | + | 1 | ) | − | 3 | ÷ | 1 | × | ( | x | − | 1 | ) | = | 4 | ( | x | − | 1 | ) | − | 7 | ÷ | 2 | × | ( | x | + | 1 | ) |
| 方程左边 = | 3 | ( | x | + | 1 | ) | − | 3 | ( | x | − | 1 | ) |
| 3 | ( | x | + | 1 | ) | − | 3 | ( | x | − | 1 | ) | = | 4 | ( | x | − | 1 | ) | − | 7 | ÷ | 2 | × | ( | x | + | 1 | ) |
| 方程左边 = | 3 | x | + | 3 | × | 1 | − | 3 | ( | x | − | 1 | ) |
| = | 3 | x | + | 3 | − | 3 | ( | x | − | 1 | ) |
| = | 3 | x | + | 3 | − | 3 | x | + | 3 | × | 1 |
| = | 3 | x | + | 3 | − | 3 | x | + | 3 |
| = | 0 | x | + | 6 |
| 6 | = | 4 | ( | x | − | 1 | ) | − | 7 | ÷ | 2 | × | ( | x | + | 1 | ) |
| 方程右边 = | 4 | ( | x | − | 1 | ) | − | 7 2 | ( | x | + | 1 | ) |
| 6 | = | 4 | ( | x | − | 1 | ) | − | 7 2 | ( | x | + | 1 | ) |
| 方程右边 = | 4 | x | − | 4 | × | 1 | − | 7 2 | ( | x | + | 1 | ) |
| = | 4 | x | − | 4 | − | 7 2 | ( | x | + | 1 | ) |
| = | 4 | x | − | 4 | − | 7 2 | x | − | 7 2 | × | 1 |
| = | 4 | x | − | 4 | − | 7 2 | x | − | 7 2 |
| = | 1 2 | x | − | 15 2 |
| 6 | = | 1 2 | x | − | 15 2 |
| - | 1 2 | x | = | - | 15 2 | − | 6 |
| - | 1 2 | x | = | - | 27 2 |
27 2 | = | 1 2 | x |
1 2 | x | = | 27 2 |
| x | = | 27 2 | ÷ | 1 2 |
| = | 27 2 | × | 2 |
| = | 27 | × | 1 |
| x | = | 27 |