| ( | x | − | 60000 | ) | × | 10 100 | − | 2520 | − | ( | x | − | 72000 | ) | × | 10 100 | − | 2520 | = | 1170 |
| 方程左边 = | ( | x | − | 60000 | ) | × | 10 100 | − | 5040 | − | ( | x | − | 72000 | ) | × | 10 100 |
| ( | x | − | 60000 | ) | × | 10 100 | − | 5040 | − | ( | x | − | 72000 | ) | × | 10 100 | = | 1170 |
| 方程左边 = | x | × | 10 100 | − | 60000 | × | 10 100 | − | 5040 | − | ( | x | − | 72000 | ) | × | 10 100 |
| = | x | × | 10 100 | − | 6000 | − | 5040 | − | ( | x | − | 72000 | ) | × | 10 100 |
| = | 10 100 | x | − | 11040 | − | ( | x | − | 72000 | ) | × | 10 100 |
| = | 10 100 | x | − | 11040 | − | x | × | 10 100 | + | 72000 | × | 10 100 |
| = | 10 100 | x | − | 11040 | − | x | × | 10 100 | + | 7200 |
| = | 0 | x | − | 3840 |
| - | 3840 | = | 1170 |
| = | 1170 | + | 3840 |