| ( | 1 | − | 4 | x | ) | ( | 1 | − | 4 | x | ) | + | x | x | = | ( | 3 | x | ) | ( | 3 | x | ) |
| 方程左边 = | 1 | ( | 1 | − | 4 | x | ) | − | 4 | x | ( | 1 | − | 4 | x | ) | + | x | x |
| = | 1 | × | 1 | − | 1 | × | 4 | x | − | 4 | x | ( | 1 | − | 4 | x | ) | + | x | x |
| = | 1 | − | 4 | x | − | 4 | x | ( | 1 | − | 4 | x | ) | + | x | x |
| = | 1 | − | 4 | x | − | 4 | x | × | 1 | + | 4 | x | × | 4 | x | + | x | x |
| = | 1 | − | 4 | x | − | 4 | x | + | 16 | x | x | + | x | x |
| = | 1 | − | 8 | x | + | 16 | x | x | + | x | x |
| 1 | − | 8 | x | + | 16 | x | x | + | x | x | = | ( | 3 | x | ) | ( | 3 | x | ) |
| 方程右边 = | 3 | x | ( | 3 | x | ) |
| = | 3 | x | × | 3 | x |
| = | 9 | x | x |
| 1 | − | 8 | x | + | 16 | x | x | + | x | x | = | 9 | x | x |