1 2 | x | + | 200 | x | × | 1 2 | + | ( | 500 | − | x | − | 200 | ) | x | × | 7 10 | = | 290 |
| 方程左边 = | 1 2 | x | + | 100 | x | + | ( | 500 | − | x | − | 200 | ) | x | × | 7 10 |
| = | 201 2 | x | + | ( | 500 | − | x | − | 200 | ) | x | × | 7 10 |
201 2 | x | + | ( | 500 | − | x | − | 200 | ) | x | × | 7 10 | = | 290 |
| 方程左边 = | 201 2 | x | + | 500 | x | × | 7 10 | − | x | x | × | 7 10 | − | 200 | x | × | 7 10 |
| = | 201 2 | x | + | 350 | x | − | x | x | × | 7 10 | − | 140 | x |
| = | 621 2 | x | − | x | x | × | 7 10 |
621 2 | x | − | x | x | × | 7 10 | = | 290 |