| ( | x | − | 5 | ) | ( | 3 | x | − | 15 | + | 2 | ) | = | 0 |
| 方程左边 = | x | ( | 3 | x | − | 15 | + | 2 | ) | − | 5 | ( | 3 | x | − | 15 | + | 2 | ) |
| = | x | × | 3 | x | − | x | × | 15 | + | x | × | 2 | − | 5 | ( | 3 | x | − | 15 | + | 2 | ) |
| = | x | × | 3 | x | − | 13 | x | − | 5 | ( | 3 | x | − | 15 | + | 2 | ) |
| = | x | × | 3 | x | − | 13 | x | − | 5 | × | 3 | x | + | 5 | × | 15 | − | 5 | × | 2 |
| = | x | × | 3 | x | − | 13 | x | − | 15 | x | + | 75 | − | 10 |
| = | x | × | 3 | x | − | 28 | x | + | 65 |
| x | × | 3 | x | − | 28 | x | + | 65 | = | 0 |
| x1= | 13 3 |
| x2=5 |