| ( | x | − | 22 | ) | ( | 1520 | − | 40 | x | + | 160 | ) | = | 0 |
| 方程左边 = | x | ( | 1520 | − | 40 | x | + | 160 | ) | − | 22 | ( | 1520 | − | 40 | x | + | 160 | ) |
| = | x | × | 1520 | − | x | × | 40 | x | + | x | × | 160 | − | 22 | ( | 1520 | − | 40 | x | + | 160 | ) |
| = | 1680 | x | − | x | × | 40 | x | − | 22 | ( | 1520 | − | 40 | x | + | 160 | ) |
| = | 1680 | x | − | x | × | 40 | x | − | 22 | × | 1520 | + | 22 | × | 40 | x | − | 22 | × | 160 |
| = | 1680 | x | − | x | × | 40 | x | − | 33440 | + | 880 | x | − | 3520 |
| = | 2560 | x | − | x | × | 40 | x | − | 36960 |
| 2560 | x | − | x | × | 40 | x | − | 36960 | = | 0 |