| 4 | x | ( | x | − | 5 2 | ) | ( | x | − | 5 2 | ) | − | 4 | = | 0 |
| 方程左边 = | 4 | x | x | ( | x | − | 5 2 | ) | − | 4 | x | × | 5 2 | ( | x | − | 5 2 | ) | − | 4 |
| = | 4 | x | x | ( | x | − | 5 2 | ) | − | 10 | x | ( | x | − | 5 2 | ) | − | 4 |
| = | 4 | x | x | x | − | 4 | x | x | × | 5 2 | − | 10 | x | ( | x | − | 5 2 | ) | − | 4 |
| = | 4 | x | x | x | − | 10 | x | x | − | 10 | x | ( | x | − | 5 2 | ) | − | 4 |
| = | 4 | x | x | x | − | 10 | x | x | − | 10 | x | x | + | 10 | x |
| = | 4 | x | x | x | − | 10 | x | x | − | 10 | x | x | + | 25 | x |
| 4 | x | x | x | − | 10 | x | x | − | 10 | x | x | + | 25 | x | = | 0 |