| 25 | ( | 1 | + | X | ) | ( | 1 | + | X | ) | = | 36 |
| 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 | = | 36 |
| X1= | - | 11 5 |
| X2= | 1 5 |