| ( | ( | 2 | d | + | 1 | ) | ( | d | + | 5 | ) | ) | = | ( | d | ( | d | + | 1 | ) | ) |
| Left side of the equation = | ( | 2 | d | + | 1 | ) | ( | d | + | 5 | ) |
| = | 2 | d | ( | d | + | 5 | ) | + | 1 | ( | d | + | 5 | ) |
| = | 2 | d | d | + | 2 | d | × | 5 | + | 1 | ( | d | + | 5 | ) |
| = | 2 | d | d | + | 10 | d | + | 1 | ( | d | + | 5 | ) |
| = | 2 | d | d | + | 10 | d | + | 1 | d | + | 1 | × | 5 |
| = | 2 | d | d | + | 10 | d | + | 1 | d | + | 5 |
| = | 2 | d | d | + | 11 | d | + | 5 |
| 2 | d | d | + | 11 | d | + | 5 | = | ( | d | ( | d | + | 1 | ) | ) |
| Right side of the equation = | d | ( | d | + | 1 | ) |
| = | d | d | + | d | × | 1 |
| 2 | d | d | + | 11 | d | + | 5 | = | d | d | + | 1 | d |