50663 100 | × | 4 | x | x | ( | 1 | − | x | ) | = | 90 | ( | 1 | + | x | ) |
| 方程左边 = | 50663 25 | x | x | ( | 1 | − | x | ) |
50663 25 | x | x | ( | 1 | − | x | ) | = | 90 | ( | 1 | + | x | ) |
| 方程左边 = | 50663 25 | x | x | × | 1 | − | 50663 25 | x | x | x |
| = | 50663 25 | x | x | − | 50663 25 | x | x | x |
50663 25 | x | x | − | 50663 25 | x | x | x | = | 90 | ( | 1 | + | x | ) |
| 方程右边 = | 90 | × | 1 | + | 90 | x |
| = | 90 | + | 90 | x |
50663 25 | x | x | − | 50663 25 | x | x | x | = | 90 | + | 90 | x |