| - | 1 20 | ( | x | − | 8 | ) | ( | x | − | 8 | ) | + | 116 5 | = | 0 |
| 方程左边 = | - | 1 20 | x | ( | x | − | 8 | ) | + | 1 20 | × | 8 | ( | x | − | 8 | ) | + | 116 5 |
| = | - | 1 20 | x | ( | x | − | 8 | ) | + | 2 5 | ( | x | − | 8 | ) | + | 116 5 |
| = | - | 1 20 | x | x | + | 1 20 | x | × | 8 | + | 2 5 | ( | x | − | 8 | ) | + | 116 5 |
| = | - | 1 20 | x | x | + | 2 5 | x | + | 2 5 | ( | x | − | 8 | ) | + | 116 5 |
| = | - | 1 20 | x | x | + | 2 5 | x | + | 2 5 | x | − | 2 5 | × | 8 | + | 116 5 |
| = | - | 1 20 | x | x | + | 2 5 | x | + | 2 5 | x | − | 16 5 | + | 116 5 |
| = | - | 1 20 | x | x | + | 4 5 | x | + | 20 |
| - | 1 20 | x | x | + | 4 5 | x | + | 20 | = | 0 |