| ( | 3 | x | + | 8 | ) | ( | 3 | x | − | 10 | ) | = | 0 |
| 方程左边 = | 3 | x | ( | 3 | x | − | 10 | ) | + | 8 | ( | 3 | x | − | 10 | ) |
| = | 3 | x | × | 3 | x | − | 3 | x | × | 10 | + | 8 | ( | 3 | x | − | 10 | ) |
| = | 9 | x | x | − | 30 | x | + | 8 | ( | 3 | x | − | 10 | ) |
| = | 9 | x | x | − | 30 | x | + | 8 | × | 3 | x | − | 8 | × | 10 |
| = | 9 | x | x | − | 30 | x | + | 24 | x | − | 80 |
| = | 9 | x | x | − | 6 | x | − | 80 |
| 9 | x | x | − | 6 | x | − | 80 | = | 0 |
| x1= | - | 8 3 |
| x2= | 10 3 |