| ( | x | − | 2 | ) | ( | x | − | 5 | ) | ( | x | − | 4 | ) | − | 24 | − | 19 | x | + | 55 | = | 0 |
| 方程左边 = | ( | x | − | 2 | ) | ( | x | − | 5 | ) | ( | x | − | 4 | ) | + | 31 | − | 19 | x |
| ( | x | − | 2 | ) | ( | x | − | 5 | ) | ( | x | − | 4 | ) | + | 31 | − | 19 | x | = | 0 |
| 方程左边 = | x | ( | x | − | 5 | ) | ( | x | − | 4 | ) | − | 2 | ( | x | − | 5 | ) | ( | x | − | 4 | ) | + | 31 | − | 19 | x |
| = | x | x | ( | x | − | 4 | ) | − | x | × | 5 | ( | x | − | 4 | ) | − | 2 | ( | x | − | 5 | ) | ( | x | − | 4 | ) | + | 31 | − | 19 | x |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | ( | x | − | 4 | ) | − | 2 | ( | x | − | 5 | ) | ( | x | − | 4 | ) |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | x | × | 5 | × | 4 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | x | × | 20 | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 1 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 1 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 1 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 1 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 1 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 9 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 9 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 9 | x | − | 2 |
| = | x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 19 | x | − | 2 |
| x | x | x | − | x | x | × | 4 | − | x | × | 5 | x | + | 19 | x | − | 2 | = | 0 |