| x | ( | x | − | 1 | ) | + | ( | x | + | 1 | ) | ( | x | + | 2 | ) | = | 0 |
| Left side of the equation = | x | x | − | x | × | 1 | + | ( | x | + | 1 | ) | ( | x | + | 2 | ) |
| = | x | x | − | 1 | x | + | x | ( | x | + | 2 | ) | + | 1 | ( | x | + | 2 | ) |
| = | x | x | − | 1 | x | + | x | x | + | x | × | 2 | + | 1 | ( | x | + | 2 | ) |
| = | x | x | + | 1 | x | + | x | x | + | 1 | ( | x | + | 2 | ) |
| = | x | x | + | 1 | x | + | x | x | + | 1 | x | + | 1 | × | 2 |
| = | x | x | + | 1 | x | + | x | x | + | 1 | x | + | 2 |
| = | x | x | + | 2 | x | + | x | x | + | 2 |
| x | x | + | 2 | x | + | x | x | + | 2 | = | 0 |