| x | × | 4 | + | 18 | x | × | 3 | + | 122 | x | × | 2 | − | 720 | x | − | 3240 | = | 0 |
| 方程左边 = | x | × | 4 | + | 54 | x | + | 244 | x | − | 720 | x | − | 3240 |
| = | - | 418 | x | − | 3240 |
| - | 418 | x | − | 3240 | = | 0 |
| - | 418 | x | = | 0 | + | 3240 |
| - | 418 | x | = | 3240 |
| - | 3240 | = | 418 | x |
| 418 | x | = | - | 3240 |
| x | = | - | 3240 | ÷ | 418 |
| = | - | 3240 | × | 1 418 |
| = | - | 1620 | × | 1 209 |
| x | = | - | 1620 209 |
| x | = | - 7.751196 |