| ( | 5 | x | + | 11 | ) | ( | 5 | x | − | 1 | ) | = | 0 |
| 方程左边 = | 5 | x | ( | 5 | x | − | 1 | ) | + | 11 | ( | 5 | x | − | 1 | ) |
| = | 5 | x | × | 5 | x | − | 5 | x | × | 1 | + | 11 | ( | 5 | x | − | 1 | ) |
| = | 25 | x | x | − | 5 | x | + | 11 | ( | 5 | x | − | 1 | ) |
| = | 25 | x | x | − | 5 | x | + | 11 | × | 5 | x | − | 11 | × | 1 |
| = | 25 | x | x | − | 5 | x | + | 55 | x | − | 11 |
| = | 25 | x | x | + | 50 | x | − | 11 |
| 25 | x | x | + | 50 | x | − | 11 | = | 0 |
| x1= | - | 11 5 |
| x2= | 1 5 |