| ( | - | 2 | x | + | 240 | ) | ( | x | − | 50 | ) | = | 0 |
| Left side of the equation = | - | 2 | x | ( | x | − | 50 | ) | + | 240 | ( | x | − | 50 | ) |
| = | - | 2 | x | x | + | 2 | x | × | 50 | + | 240 | ( | x | − | 50 | ) |
| = | - | 2 | x | x | + | 100 | x | + | 240 | ( | x | − | 50 | ) |
| = | - | 2 | x | x | + | 100 | x | + | 240 | x | − | 240 | × | 50 |
| = | - | 2 | x | x | + | 100 | x | + | 240 | x | − | 12000 |
| = | - | 2 | x | x | + | 340 | x | − | 12000 |
| - | 2 | x | x | + | 340 | x | − | 12000 | = | 0 |