| 1280 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | − | 1280 | = | 1600 |
| Left side of the equation = | 1280 | × | 1 | ( | 1 | + | x | ) | + | 1280 | x | ( | 1 | + | x | ) | − | 1280 |
| = | 1280 | ( | 1 | + | x | ) | + | 1280 | x | ( | 1 | + | x | ) | − | 1280 |
| = | 1280 | × | 1 | + | 1280 | x | + | 1280 | x | ( | 1 | + | x | ) | − | 1280 |
| = | 1280 | + | 1280 | x | + | 1280 | x | ( | 1 | + | x | ) | − | 1280 |
| = | 0 | + | 1280 | x | + | 1280 | x | ( | 1 | + | x | ) |
| = | 0 | + | 1280 | x | + | 1280 | x | × | 1 | + | 1280 | x | x |
| = | 0 | + | 1280 | x | + | 1280 | x | + | 1280 | x | x |
| = | 0 | + | 2560 | x | + | 1280 | x | x |
| 0 | + | 2560 | x | + | 1280 | x | x | = | 1600 |
| x1= | - | 5 2 |
| x2= | 1 2 |