| ( | 1 | − | 3 | k | ) | ( | 1 | − | 3 | k | ) | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) | = | 9 | ( | k | + | 1 | ) | ( | k | + | 1 | ) |
| Left side of the equation = | 1 | ( | 1 | − | 3 | k | ) | − | 3 | k | ( | 1 | − | 3 | k | ) | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) |
| = | 1 | × | 1 | − | 1 | × | 3 | k | − | 3 | k | ( | 1 | − | 3 | k | ) | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) |
| = | 1 | − | 3 | k | − | 3 | k | ( | 1 | − | 3 | k | ) | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) |
| = | 1 | − | 3 | k | − | 3 | k | × | 1 | + | 3 | k | × | 3 | k | − | 4 | ( | 2 | k | − | 2 | ) |
| = | 1 | − | 3 | k | − | 3 | k | + | 9 | k | k | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) |
| = | 1 | − | 6 | k | + | 9 | k | k | − | 4 | ( | 2 | k | − | 2 | ) | ( | k | + | 1 | ) |
| = | 1 | − | 6 | k | + | 9 | k | k | − | 4 | × | 2 | k | ( | k | + | 1 | ) | + | 4 | × | 2 |
| = | 1 | − | 6 | k | + | 9 | k | k | − | 8 | k | ( | k | + | 1 | ) | + | 8 | ( | k | + | 1 | ) |
| = | 1 | − | 6 | k | + | 9 | k | k | − | 8 | k | k | − | 8 | k | × | 1 |
| = | 1 | − | 6 | k | + | 9 | k | k | − | 8 | k | k | − | 8 | k | + | 8 |
| = | 1 | − | 14 | k | + | 9 | k | k | − | 8 | k | k | + | 8 | ( | k | + | 1 | ) |
| = | 1 | − | 14 | k | + | 9 | k | k | − | 8 | k | k | + | 8 | k | + | 8 |
| = | 1 | − | 14 | k | + | 9 | k | k | − | 8 | k | k | + | 8 | k | + | 8 |
| = | 9 | − | 6 | k | + | 9 | k | k | − | 8 | k | k |
| 9 | − | 6 | k | + | 9 | k | k | − | 8 | k | k | = | 9 | ( | k | + | 1 | ) | ( | k | + | 1 | ) |
| Right side of the equation = | 9 | k | ( | k | + | 1 | ) | + | 9 | × | 1 | ( | k | + | 1 | ) |
| = | 9 | k | ( | k | + | 1 | ) | + | 9 | ( | k | + | 1 | ) |
| = | 9 | k | k | + | 9 | k | × | 1 | + | 9 | ( | k | + | 1 | ) |
| = | 9 | k | k | + | 9 | k | + | 9 | ( | k | + | 1 | ) |
| = | 9 | k | k | + | 9 | k | + | 9 | k | + | 9 | × | 1 |
| = | 9 | k | k | + | 9 | k | + | 9 | k | + | 9 |
| = | 9 | k | k | + | 18 | k | + | 9 |
| 9 | − | 6 | k | + | 9 | k | k | − | 8 | k | k | = | 9 | k | k | + | 18 | k | + | 9 |