| ( | x | − | 3 | ) | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) | = | 0 |
| 方程左边 = | x | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) | − | 3 | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) |
| = | x | × | 500 | − | x | × | 10 | x | − | x | × | 4 | ÷ | 1 10 | − | 3 | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) |
| = | x | × | 500 | − | x | × | 10 | x | − | x | × | 40 | − | 3 | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) |
| = | 460 | x | − | x | × | 10 | x | − | 3 | ( | 500 | − | 10 | x | − | 4 | ÷ | 1 10 | ) |
| = | 460 | x | − | x | × | 10 | x | − | 3 | × | 500 | + | 3 | × | 10 | x | + | 3 | × | 4 |
| = | 460 | x | − | x | × | 10 | x | − | 1500 | + | 30 | x | + | 120 |
| = | 490 | x | − | x | × | 10 | x | − | 1380 |
| 490 | x | − | x | × | 10 | x | − | 1380 | = | 0 |