| ( | X | + | 1 | ) | ( | X | + | 1 | ) | = | ( | 2 | X | − | 1 | ) | ( | 2 | X | − | 1 | ) |
| 方程左边 = | X | ( | X | + | 1 | ) | + | 1 | ( | X | + | 1 | ) |
| = | X | X | + | X | × | 1 | + | 1 | ( | X | + | 1 | ) |
| = | X | X | + | 1 | X | + | 1 | X | + | 1 | × | 1 |
| = | X | X | + | 1 | X | + | 1 | X | + | 1 |
| = | X | X | + | 2 | X | + | 1 |
| X | X | + | 2 | X | + | 1 | = | ( | 2 | X | − | 1 | ) | ( | 2 | X | − | 1 | ) |
| 方程右边 = | 2 | X | ( | 2 | X | − | 1 | ) | − | 1 | ( | 2 | X | − | 1 | ) |
| = | 2 | X | × | 2 | X | − | 2 | X | × | 1 | − | 1 | ( | 2 | X | − | 1 | ) |
| = | 4 | X | X | − | 2 | X | − | 1 | ( | 2 | X | − | 1 | ) |
| = | 4 | X | X | − | 2 | X | − | 1 | × | 2 | X | + | 1 | × | 1 |
| = | 4 | X | X | − | 2 | X | − | 2 | X | + | 1 |
| = | 4 | X | X | − | 4 | X | + | 1 |
| X | X | + | 2 | X | + | 1 | = | 4 | X | X | − | 4 | X | + | 1 |