| 25 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | = | 64 |
| 方程左边 = | 25 | × | 1 | ( | 1 | + | x | ) | + | 25 | x | ( | 1 | + | x | ) |
| = | 25 | ( | 1 | + | x | ) | + | 25 | x | ( | 1 | + | x | ) |
| = | 25 | × | 1 | + | 25 | x | + | 25 | x | ( | 1 | + | x | ) |
| = | 25 | + | 25 | x | + | 25 | x | ( | 1 | + | x | ) |
| = | 25 | + | 25 | x | + | 25 | x | × | 1 | + | 25 | x | x |
| = | 25 | + | 25 | x | + | 25 | x | + | 25 | x | x |
| = | 25 | + | 50 | x | + | 25 | x | x |
| 25 | + | 50 | x | + | 25 | x | x | = | 64 |
| x1= | - | 13 5 |
| x2= | 3 5 |