| ( | 8 | x | − | 4 | x | ) | ( | 4 | + | 2 | x | ) | = | 0 |
| 方程左边 = | 8 | x | ( | 4 | + | 2 | x | ) | − | 4 | x | ( | 4 | + | 2 | x | ) |
| = | 8 | x | × | 4 | + | 8 | x | × | 2 | x | − | 4 | x | ( | 4 | + | 2 | x | ) |
| = | 32 | x | + | 16 | x | x | − | 4 | x | ( | 4 | + | 2 | x | ) |
| = | 32 | x | + | 16 | x | x | − | 4 | x | × | 4 | − | 4 | x | × | 2 | x |
| = | 32 | x | + | 16 | x | x | − | 16 | x | − | 8 | x | x |
| = | 16 | x | + | 16 | x | x | − | 8 | x | x |
| 16 | x | + | 16 | x | x | − | 8 | x | x | = | 0 |