| 4 | ( | x | + | 45 | ) | = | 9 2 | ( | x | − | 45 | ) |
| 方程左边 = | 4 | x | + | 4 | × | 45 |
| = | 4 | x | + | 180 |
| 4 | x | + | 180 | = | 9 2 | ( | x | − | 45 | ) |
| 方程右边 = | 9 2 | x | − | 9 2 | × | 45 |
| = | 9 2 | x | − | 405 2 |
| 4 | x | + | 180 | = | 9 2 | x | − | 405 2 |
| 4 | x | − | 9 2 | x | = | - | 405 2 | − | 180 |
| - | 1 2 | x | = | - | 405 2 | − | 180 |
| - | 1 2 | x | = | - | 765 2 |
765 2 | = | 1 2 | x |
1 2 | x | = | 765 2 |
| x | = | 765 2 | ÷ | 1 2 |
| = | 765 2 | × | 2 |
| = | 765 | × | 1 |
| x | = | 765 |