| ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) | = | 0 |
| 方程左边 = | 1 | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | × | 1 | ( | 1 | + | 3 | x | ) | + | 1 | × | 2 | x | ( | 1 | + | 3 | x | ) | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | ( | 1 | + | 3 | x | ) | + | 2 | x | ( | 1 | + | 3 | x | ) | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | × | 1 | + | 1 | × | 3 | x | + | 2 | x | ( | 1 | + | 3 | x | ) | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | + | 3 | x | + | 2 | x | ( | 1 | + | 3 | x | ) | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | + | 3 | x | + | 2 | x | × | 1 | + | 2 | x | × | 3 | x | + | x | ( | 1 | + | 2 | x | ) |
| = | 1 | + | 3 | x | + | 2 | x | + | 6 | x | x | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | + | 5 | x | + | 6 | x | x | + | x | ( | 1 | + | 2 | x | ) | ( | 1 | + | 3 | x | ) |
| = | 1 | + | 5 | x | + | 6 | x | x | + | x | × | 1 | ( | 1 | + | 3 | x | ) | + | x | × | 2 | x |
| = | 1 | + | 5 | x | + | 6 | x | x | + | x | × | 1 | × | 1 | + | x | × | 1 | × | 3 |
| = | 1 | + | 5 | x | + | 6 | x | x | + | x | × | 1 | + | x | × | 3 | x | + | x |
| = | 1 | + | 6 | x | + | 6 | x | x | + | x | × | 3 | x | + | x | × | 2 | x |
| = | 1 | + | 6 | x | + | 6 | x | x | + | x | × | 3 | x | + | x | × | 2 | x |
| = | 1 | + | 6 | x | + | 6 | x | x | + | x | × | 3 | x | + | x | × | 2 | x |
| 1 | + | 6 | x | + | 6 | x | x | + | x | × | 3 | x | + | x | × | 2 | x | = | 0 |
| x2= | - | 1 2 |
| x3= | - | 1 3 |