| ( | 50 | − | 2 | x | ) | ( | 30 | − | 3 2 | x | ) | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) | = | 2430 |
| 方程左边 = | 50 | ( | 30 | − | 3 2 | x | ) | − | 2 | x | ( | 30 | − | 3 2 | x | ) | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 50 | × | 30 | − | 50 | × | 3 2 | x | − | 2 | x | ( | 30 | − | 3 2 | x | ) | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 75 | x | − | 2 | x | ( | 30 | − | 3 2 | x | ) | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 75 | x | − | 2 | x | × | 30 | + | 2 | x | × | 3 2 | x | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 75 | x | − | 60 | x | + | 3 | x | x | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 135 | x | + | 3 | x | x | + | ( | 30 | − | 3 2 | x | ) | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 135 | x | + | 3 | x | x | + | 30 | ( | 50 | − | 3 | x | ) | − | 3 2 | x | ( | 50 | − | 3 | x | ) |
| = | 1500 | − | 135 | x | + | 3 | x | x | + | 30 | × | 50 | − | 30 | × | 3 | x | − | 3 2 |
| = | 1500 | − | 135 | x | + | 3 | x | x | + | 1500 | − | 90 | x | − | 3 2 | x | ( | 50 | − | 3 | x | ) |
| = | 3000 | − | 225 | x | + | 3 | x | x | − | 3 2 | x | ( | 50 | − | 3 | x | ) |
| = | 3000 | − | 225 | x | + | 3 | x | x | − | 3 2 | x | × | 50 | + | 3 2 | x | × | 3 |
| = | 3000 | − | 225 | x | + | 3 | x | x | − | 75 | x | + | 9 2 | x | x |
| = | 3000 | − | 300 | x | + | 3 | x | x | + | 9 2 | x | x |
| 3000 | − | 300 | x | + | 3 | x | x | + | 9 2 | x | x | = | 2430 |