| ( | x | + | 1 | ) | ( | x | + | 2 | ) | ( | x | + | 2 | ) | = | 120 |
| Left side of the equation = | x | ( | x | + | 2 | ) | ( | x | + | 2 | ) | + | 1 | ( | x | + | 2 | ) | ( | x | + | 2 | ) |
| = | x | x | ( | x | + | 2 | ) | + | x | × | 2 | ( | x | + | 2 | ) | + | 1 | ( | x | + | 2 | ) | ( | x | + | 2 | ) |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | ( | x | + | 2 | ) | + | 1 | ( | x | + | 2 | ) | ( | x | + | 2 | ) |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | x | × | 2 | × | 2 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | x | × | 4 | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 4 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 4 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 4 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 4 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 6 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 6 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 6 | x | + | 1 |
| = | x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 8 | x | + | 1 |
| x | x | x | + | x | x | × | 2 | + | x | × | 2 | x | + | 8 | x | + | 1 | = | 120 |