| 10 | x | ( | x | − | 3 | ) | = | ( | 10 | x | + | ( | x | − | 3 | ) | ) | × | 2 | ÷ | 7 |
| 方程左边 = | 10 | x | x | − | 10 | x | × | 3 |
| = | 10 | x | x | − | 30 | x |
| 10 | x | x | − | 30 | x | = | ( | 10 | x | + | ( | x | − | 3 | ) | ) | × | 2 | ÷ | 7 |
| 方程右边 = | ( | 10 | x | + | ( | x | − | 3 | ) | ) | × | 2 7 |
| 10 | x | x | − | 30 | x | = | ( | 10 | x | + | ( | x | − | 3 | ) | ) | × | 2 7 |
| 方程右边 = | 10 | x | × | 2 7 | + | ( | x | − | 3 | ) | × | 2 7 |
| = | 20 7 | x | + | ( | x | − | 3 | ) | × | 2 7 |
| = | 20 7 | x | + | x | × | 2 7 | − | 3 | × | 2 7 |
| = | 20 7 | x | + | x | × | 2 7 | − | 6 7 |
| = | 22 7 | x | − | 6 7 |
| 10 | x | x | − | 30 | x | = | 22 7 | x | − | 6 7 |