| ( | 5 | + | x | ) | ( | 5 | + | x | − | 1 | ) | = | 33 |
| Left side of the equation = | 5 | ( | 5 | + | x | − | 1 | ) | + | x | ( | 5 | + | x | − | 1 | ) |
| = | 5 | × | 5 | + | 5 | x | − | 5 | × | 1 | + | x | ( | 5 | + | x | − | 1 | ) |
| = | 25 | + | 5 | x | − | 5 | + | x | ( | 5 | + | x | − | 1 | ) |
| = | 20 | + | 5 | x | + | x | ( | 5 | + | x | − | 1 | ) |
| = | 20 | + | 5 | x | + | x | × | 5 | + | x | x | − | x | × | 1 |
| = | 20 | + | 9 | x | + | x | x |
| 20 | + | 9 | x | + | x | x | = | 33 |