| ( | x | + | 3 | ) | ( | 4 | − | 1 2 | x | ) | = | 15 |
| Left side of the equation = | x | ( | 4 | − | 1 2 | x | ) | + | 3 | ( | 4 | − | 1 2 | x | ) |
| = | x | × | 4 | − | x | × | 1 2 | x | + | 3 | ( | 4 | − | 1 2 | x | ) |
| = | 4 | x | − | x | × | 1 2 | x | + | 3 | × | 4 | − | 3 | × | 1 2 | x |
| = | 4 | x | − | x | × | 1 2 | x | + | 12 | − | 3 2 | x |
| = | 5 2 | x | − | x | × | 1 2 | x | + | 12 |
5 2 | x | − | x | × | 1 2 | x | + | 12 | = | 15 |