17658 25 | x | = | 30 | ( | x | − | 20 | ) | ( | x | − | 20 | ) |
| Right side of the equation = | 30 | x | ( | x | − | 20 | ) | − | 30 | × | 20 | ( | x | − | 20 | ) |
| = | 30 | x | ( | x | − | 20 | ) | − | 600 | ( | x | − | 20 | ) |
| = | 30 | x | x | − | 30 | x | × | 20 | − | 600 | ( | x | − | 20 | ) |
| = | 30 | x | x | − | 600 | x | − | 600 | ( | x | − | 20 | ) |
| = | 30 | x | x | − | 600 | x | − | 600 | x | + | 600 | × | 20 |
| = | 30 | x | x | − | 600 | x | − | 600 | x | + | 12000 |
| = | 30 | x | x | − | 1200 | x | + | 12000 |
17658 25 | x | = | 30 | x | x | − | 1200 | x | + | 12000 |