| ( | x | − | 1 | ) | ( | x | + | 1 | ) | × | 2 | = | 0 |
| 方程左边 = | x | ( | x | + | 1 | ) | × | 2 | − | 1 | ( | x | + | 1 | ) | × | 2 |
| = | x | ( | x | + | 1 | ) | × | 2 | − | 2 | ( | x | + | 1 | ) |
| = | x | x | × | 2 | + | x | × | 1 | × | 2 | − | 2 | ( | x | + | 1 | ) |
| = | x | x | × | 2 | + | x | × | 2 | − | 2 | ( | x | + | 1 | ) |
| = | x | x | × | 2 | + | 2 | x | − | 2 | x | − | 2 | × | 1 |
| = | x | x | × | 2 | + | 2 | x | − | 2 | x | − | 2 |
| = | x | x | × | 2 | + | 0 | x | − | 2 |
| x | x | × | 2 | − | 2 | = | 0 |