| ( | 3 | k | + | 1 | ) | ( | 3 | k | + | 1 | ) | − | 4 | ( | 3 | k | + | 4 | ) | = | 0 |
| Left side of the equation = | 3 | k | ( | 3 | k | + | 1 | ) | + | 1 | ( | 3 | k | + | 1 | ) | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 3 | k | × | 3 | k | + | 3 | k | × | 1 | + | 1 | ( | 3 | k | + | 1 | ) | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 9 | k | k | + | 3 | k | + | 1 | ( | 3 | k | + | 1 | ) | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 9 | k | k | + | 3 | k | + | 1 | × | 3 | k | + | 1 | × | 1 | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 9 | k | k | + | 3 | k | + | 3 | k | + | 1 | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 9 | k | k | + | 6 | k | + | 1 | − | 4 | ( | 3 | k | + | 4 | ) |
| = | 9 | k | k | + | 6 | k | + | 1 | − | 4 | × | 3 | k | − | 4 | × | 4 |
| = | 9 | k | k | + | 6 | k | + | 1 | − | 12 | k | − | 16 |
| = | 9 | k | k | − | 6 | k | − | 15 |
| 9 | k | k | − | 6 | k | − | 15 | = | 0 |
| k2= | 5 3 |