| 4 | = | ( | k | + | 1 | − | 3 | ) | ( | k | + | 1 | ) |
| Right side of the equation = | k | ( | k | + | 1 | ) | + | 1 | ( | k | + | 1 | ) | − | 3 | ( | k | + | 1 | ) |
| = | k | k | + | k | × | 1 | + | 1 | ( | k | + | 1 | ) | − | 3 | ( | k | + | 1 | ) |
| = | k | k | + | 1 | k | + | 1 | k | + | 1 | × | 1 | − | 3 | ( | k | + | 1 | ) |
| = | k | k | + | 1 | k | + | 1 | k | + | 1 | − | 3 | ( | k | + | 1 | ) |
| = | k | k | + | 2 | k | + | 1 | − | 3 | ( | k | + | 1 | ) |
| = | k | k | + | 2 | k | + | 1 | − | 3 | k | − | 3 | × | 1 |
| = | k | k | + | 2 | k | + | 1 | − | 3 | k | − | 3 |
| = | k | k | − | 1 | k | − | 2 |
| 4 | = | k | k | − | 1 | k | − | 2 |