| 600 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | = | 864 |
| 方程左边 = | 600 | × | 1 | ( | 1 | + | x | ) | + | 600 | x | ( | 1 | + | x | ) |
| = | 600 | ( | 1 | + | x | ) | + | 600 | x | ( | 1 | + | x | ) |
| = | 600 | × | 1 | + | 600 | x | + | 600 | x | ( | 1 | + | x | ) |
| = | 600 | + | 600 | x | + | 600 | x | ( | 1 | + | x | ) |
| = | 600 | + | 600 | x | + | 600 | x | × | 1 | + | 600 | x | x |
| = | 600 | + | 600 | x | + | 600 | x | + | 600 | x | x |
| = | 600 | + | 1200 | x | + | 600 | x | x |
| 600 | + | 1200 | x | + | 600 | x | x | = | 864 |
| x1= | - | 11 5 |
| x2= | 1 5 |