| - | x | ( | 4 | − | x | ) | ( | 1 | − | x | ) | + | 4 | ( | 1 | − | x | ) | = | 0 |
| Left side of the equation = | - | x | × | 4 | ( | 1 | − | x | ) | + | x | x | ( | 1 | − | x | ) | + | 4 | ( | 1 | − | x | ) |
| = | - | x | × | 4 | × | 1 | + | x | × | 4 | x | + | x | x | ( | 1 | − | x | ) | + | 4 | ( | 1 | − | x | ) |
| = | - | x | × | 4 | + | x | × | 4 | x | + | x | x | ( | 1 | − | x | ) | + | 4 | ( | 1 | − | x | ) |
| = | - | 4 | x | + | x | × | 4 | x | + | x | x | × | 1 | − | x | x | x | + | 4 |
| = | - | 4 | x | + | x | × | 4 | x | + | x | x | × | 1 | − | x | x | x | + | 4 |
| = | - | 4 | x | + | x | × | 4 | x | + | x | x | × | 1 | − | x | x | x | + | 4 |
| = | - | 8 | x | + | x | × | 4 | x | + | x | x | × | 1 | − | x | x | x | + | 4 |
| - | 8 | x | + | x | × | 4 | x | + | x | x | × | 1 | − | x | x | x | + | 4 | = | 0 |