| x | x | − | 700 | × | 700 | = | ( | x | − | 217 | ) | ( | x | − | 271 | ) |
| 方程左边 = | x | x | − | 490000 |
| x | x | − | 490000 | = | ( | x | − | 217 | ) | ( | x | − | 271 | ) |
| 方程右边 = | x | ( | x | − | 271 | ) | − | 217 | ( | x | − | 271 | ) |
| = | x | x | − | x | × | 271 | − | 217 | ( | x | − | 271 | ) |
| = | x | x | − | 271 | x | − | 217 | x | + | 217 | × | 271 |
| = | x | x | − | 271 | x | − | 217 | x | + | 58807 |
| = | x | x | − | 488 | x | + | 58807 |
| x | x | − | 490000 | = | x | x | − | 488 | x | + | 58807 |