| 4 | = | ( | 3 | + | x | ) | ( | 3 | − | x | − | 1 | ) |
| Right side of the equation = | 3 | ( | 3 | − | x | − | 1 | ) | + | x | ( | 3 | − | x | − | 1 | ) |
| = | 3 | × | 3 | − | 3 | x | − | 3 | × | 1 | + | x | ( | 3 | − | x | − | 1 | ) |
| = | 9 | − | 3 | x | − | 3 | + | x | ( | 3 | − | x | − | 1 | ) |
| = | 6 | − | 3 | x | + | x | ( | 3 | − | x | − | 1 | ) |
| = | 6 | − | 3 | x | + | x | × | 3 | − | x | x | − | x | × | 1 |
| = | 6 | − | 1 | x | − | x | x |
| 4 | = | 6 | − | 1 | x | − | x | x |