| ( | 2 | x | + | 10 | ) | ( | 4 | x | + | 10 | ) | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) | = | 0 |
| 方程左边 = | 2 | x | ( | 4 | x | + | 10 | ) | + | 10 | ( | 4 | x | + | 10 | ) | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 2 | x | × | 4 | x | + | 2 | x | × | 10 | + | 10 | ( | 4 | x | + | 10 | ) | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 20 | x | + | 10 | ( | 4 | x | + | 10 | ) | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 20 | x | + | 10 | × | 4 | x | + | 10 | × | 10 | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 20 | x | + | 40 | x | + | 100 | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 60 | x | + | 100 | − | ( | 3 | x | + | 9 | ) | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 60 | x | + | 100 | − | 3 | x | ( | 3 | x | − | 9 | ) | − | 9 | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 60 | x | + | 100 | − | 3 | x | × | 3 | x | + | 3 | x |
| = | 8 | x | x | + | 60 | x | + | 100 | − | 9 | x | x | + | 27 | x | − | 9 |
| = | 8 | x | x | + | 87 | x | + | 100 | − | 9 | x | x | − | 9 | ( | 3 | x | − | 9 | ) |
| = | 8 | x | x | + | 87 | x | + | 100 | − | 9 | x | x | − | 9 | × | 3 | x |
| = | 8 | x | x | + | 87 | x | + | 100 | − | 9 | x | x | − | 27 | x | + | 81 |
| = | 8 | x | x | + | 60 | x | + | 181 | − | 9 | x | x |
| 8 | x | x | + | 60 | x | + | 181 | − | 9 | x | x | = | 0 |