| 2 | ( | x | + | 7 200 | x | ) | + | 7 200 | ( | x | + | 7 200 | x | ) | + | 671 2 | = | x | + | 22 500 | x |
| 方程左边 = | 2 | x | + | 2 | × | 7 200 | x | + | 7 200 | ( | x | + | 7 200 | x | ) | + | 671 2 |
| = | 2 | x | + | 7 100 | x | + | 7 200 | ( | x | + | 7 200 | x | ) | + | 671 2 |
| = | 207 100 | x | + | 7 200 | ( | x | + | 7 200 | x | ) | + | 671 2 |
| = | 207 100 | x | + | 7 200 | x | + | 7 200 | × | 7 200 | x | + | 671 2 |
| = | 207 100 | x | + | 7 200 | x | + | 49 40000 | x | + | 671 2 |
| = | 84249 40000 | x | + | 671 2 |
84249 40000 | x | + | 671 2 | = | x | + | 22 500 | x |
| 方程右边 = | 261 250 | x |
84249 40000 | x | + | 671 2 | = | 261 250 | x |
84249 40000 | x | − | 261 250 | x | = | - | 671 2 |
42489 40000 | x | = | - | 671 2 |
| x | = | - | 671 2 | ÷ | 42489 40000 |
| = | - | 671 2 | × | 40000 42489 |
| = | - | 671 | × | 20000 42489 |
| x | = | - | 13420000 42489 |
| x | = | - 315.846454 |