| ( | 2 | x | − | 1 | ) | ( | 2 | x | + | 5 | ) | = | 0 |
| Left side of the equation = | 2 | x | ( | 2 | x | + | 5 | ) | − | 1 | ( | 2 | x | + | 5 | ) |
| = | 2 | x | × | 2 | x | + | 2 | x | × | 5 | − | 1 | ( | 2 | x | + | 5 | ) |
| = | 4 | x | x | + | 10 | x | − | 1 | ( | 2 | x | + | 5 | ) |
| = | 4 | x | x | + | 10 | x | − | 1 | × | 2 | x | − | 1 | × | 5 |
| = | 4 | x | x | + | 10 | x | − | 2 | x | − | 5 |
| = | 4 | x | x | + | 8 | x | − | 5 |
| 4 | x | x | + | 8 | x | − | 5 | = | 0 |
| x1= | - | 5 2 |
| x2= | 1 2 |