| ( | x | + | 1 | ) | × | 2 | − | 9 | x | × | 2 | = | 0 |
| 方程左边 = | ( | x | + | 1 | ) | × | 2 | − | 18 | x |
| ( | x | + | 1 | ) | × | 2 | − | 18 | x | = | 0 |
| 方程左边 = | x | × | 2 | + | 1 | × | 2 | − | 18 | x |
| = | x | × | 2 | + | 2 | − | 18 | x |
| = | - | 16 | x | + | 2 |
| - | 16 | x | + | 2 | = | 0 |
| - | 16 | x | = | 0 | − | 2 |
| - | 16 | x | = | - | 2 |
| 2 | = | 16 | x |
| 16 | x | = | 2 |
| x | = | 2 | ÷ | 16 |
| = | 2 | × | 1 16 |
| = | 1 | × | 1 8 |
| x | = | 1 8 |
| x | = | 0.125 |