| 3 | ( | x | + | 5 | ) | ( | x | + | 5 | ) | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) | = | 180 |
| 方程左边 = | 3 | x | ( | x | + | 5 | ) | + | 3 | × | 5 | ( | x | + | 5 | ) | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) |
| = | 3 | x | ( | x | + | 5 | ) | + | 15 | ( | x | + | 5 | ) | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) |
| = | 3 | x | x | + | 3 | x | × | 5 | + | 15 | ( | x | + | 5 | ) | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) |
| = | 3 | x | x | + | 15 | x | + | 15 | ( | x | + | 5 | ) | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) |
| = | 3 | x | x | + | 15 | x | + | 15 | x | + | 15 | × | 5 | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) |
| = | 3 | x | x | + | 15 | x | + | 15 | x | + | 75 | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) |
| = | 3 | x | x | + | 30 | x | + | 75 | − | 2 | ( | x | − | 3 | ) | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) |
| = | 3 | x | x | + | 30 | x | + | 75 | − | 2 | x | ( | x | − | 3 | ) | + | 2 | × | 3 | ( | x | − | 3 | ) |
| = | 3 | x | x | + | 30 | x | + | 75 | − | 2 | x | ( | x | − | 3 | ) | + | 6 | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) |
| = | 3 | x | x | + | 30 | x | + | 75 | − | 2 | x | x | + | 2 | x | × | 3 |
| = | 3 | x | x | + | 30 | x | + | 75 | − | 2 | x | x | + | 6 | x | + | 6 |
| = | 3 | x | x | + | 36 | x | + | 75 | − | 2 | x | x | + | 6 | ( | x | − | 3 | ) | − | ( | x | + | 9 | ) |
| = | 3 | x | x | + | 36 | x | + | 75 | − | 2 | x | x | + | 6 | x | − | 6 |
| = | 3 | x | x | + | 36 | x | + | 75 | − | 2 | x | x | + | 6 | x | − | 18 |
| = | 3 | x | x | + | 42 | x | + | 57 | − | 2 | x | x | − | ( | x | + | 9 | ) | ( | x | − | 9 | ) |
| = | 3 | x | x | + | 42 | x | + | 57 | − | 2 | x | x | − | x | ( | x | − | 9 | ) | − | 9 |
| = | 3 | x | x | + | 42 | x | + | 57 | − | 2 | x | x | − | x | x | + | x |
| = | 3 | x | x | + | 51 | x | + | 57 | − | 2 | x | x | − | x | x | − | 9 |
| = | 3 | x | x | + | 51 | x | + | 57 | − | 2 | x | x | − | x | x | − | 9 |
| = | 3 | x | x | + | 51 | x | + | 57 | − | 2 | x | x | − | x | x | − | 9 |
| = | 3 | x | x | + | 42 | x | + | 138 | − | 2 | x | x | − | x | x |
| 3 | x | x | + | 42 | x | + | 138 | − | 2 | x | x | − | x | x | = | 180 |