| 256 | ( | x | + | 1 | ) | ( | x | + | 1 | ) | = | 400 |
| Left side of the equation = | 256 | x | ( | x | + | 1 | ) | + | 256 | × | 1 | ( | x | + | 1 | ) |
| = | 256 | x | ( | x | + | 1 | ) | + | 256 | ( | x | + | 1 | ) |
| = | 256 | x | x | + | 256 | x | × | 1 | + | 256 | ( | x | + | 1 | ) |
| = | 256 | x | x | + | 256 | x | + | 256 | ( | x | + | 1 | ) |
| = | 256 | x | x | + | 256 | x | + | 256 | x | + | 256 | × | 1 |
| = | 256 | x | x | + | 256 | x | + | 256 | x | + | 256 |
| = | 256 | x | x | + | 512 | x | + | 256 |
| 256 | x | x | + | 512 | x | + | 256 | = | 400 |
| x1= | - | 9 4 |
| x2= | 1 4 |