| ( | 5 | x | − | 7 | ) | ( | 4 | x | + | 11 | ) | = | 0 |
| Left side of the equation = | 5 | x | ( | 4 | x | + | 11 | ) | − | 7 | ( | 4 | x | + | 11 | ) |
| = | 5 | x | × | 4 | x | + | 5 | x | × | 11 | − | 7 | ( | 4 | x | + | 11 | ) |
| = | 20 | x | x | + | 55 | x | − | 7 | ( | 4 | x | + | 11 | ) |
| = | 20 | x | x | + | 55 | x | − | 7 | × | 4 | x | − | 7 | × | 11 |
| = | 20 | x | x | + | 55 | x | − | 28 | x | − | 77 |
| = | 20 | x | x | + | 27 | x | − | 77 |
| 20 | x | x | + | 27 | x | − | 77 | = | 0 |
| x1= | - | 11 4 |
| x2= | 7 5 |