| ( | 140 | − | x | ) | ( | x | + | 10 | ) | = | 3 2 | x | ( | 130 | − | x | ) |
| 方程左边 = | 140 | ( | x | + | 10 | ) | − | x | ( | x | + | 10 | ) |
| = | 140 | x | + | 140 | × | 10 | − | x | ( | x | + | 10 | ) |
| = | 140 | x | + | 1400 | − | x | ( | x | + | 10 | ) |
| = | 140 | x | + | 1400 | − | x | x | − | x | × | 10 |
| = | 130 | x | + | 1400 | − | x | x |
| 130 | x | + | 1400 | − | x | x | = | 3 2 | x | ( | 130 | − | x | ) |
| 方程右边 = | 3 2 | x | × | 130 | − | 3 2 | x | x |
| = | 195 | x | − | 3 2 | x | x |
| 130 | x | + | 1400 | − | x | x | = | 195 | x | − | 3 2 | x | x |