| ( | x | − | 7 200 | ) | ( | 2 | x | + | 317 100 | ) | = | 0 |
| 方程左边 = | x | ( | 2 | x | + | 317 100 | ) | − | 7 200 | ( | 2 | x | + | 317 100 | ) |
| = | x | × | 2 | x | + | x | × | 317 100 | − | 7 200 | ( | 2 | x | + | 317 100 | ) |
| = | x | × | 2 | x | + | 317 100 | x | − | 7 200 | × | 2 | x | − | 7 200 | × | 317 100 |
| = | x | × | 2 | x | + | 317 100 | x | − | 7 100 | x | − | 2219 20000 |
| = | x | × | 2 | x | + | 31 10 | x | − | 2219 20000 |
| x | × | 2 | x | + | 31 10 | x | − | 2219 20000 | = | 0 |
| x1= | - | 317 200 |
| x2= | 7 200 |