| ( | a | − | 9 100 | ) | ( | a | − | 17 25 | ) | = | 9 50 | × | 9 50 |
| 方程左边 = | a | ( | a | − | 17 25 | ) | − | 9 100 | ( | a | − | 17 25 | ) |
| = | a | a | − | a | × | 17 25 | − | 9 100 | ( | a | − | 17 25 | ) |
| = | a | a | − | 17 25 | a | − | 9 100 | a | + | 9 100 | × | 17 25 |
| = | a | a | − | 17 25 | a | − | 9 100 | a | + | 153 2500 |
| = | a | a | − | 77 100 | a | + | 153 2500 |
| a | a | − | 77 100 | a | + | 153 2500 | = | 9 50 | × | 9 50 |
| 方程右边 = | 81 2500 |
| a | a | − | 77 100 | a | + | 153 2500 | = | 81 2500 |