| ( | 5 2 | x | + | 12 | ) | ÷ | ( | 72 | + | x | ) | = | 1 2 |
| 方程两边同时乘以: | ( | 72 | + | x | ) |
| ( | 5 2 | x | + | 12 | ) | = | 1 2 | ( | 72 | + | x | ) |
5 2 | x | + | 12 | = | 1 2 | ( | 72 | + | x | ) |
5 2 | x | + | 12 | = | 1 2 | × | 72 | + | 1 2 | x |
5 2 | x | + | 12 | = | 36 | + | 1 2 | x |
5 2 | x | − | 1 2 | x | = | 36 | − | 12 |
| 2 | x | = | 36 | − | 12 |
| 2 | x | = | 24 |
| x | = | 24 | ÷ | 2 |
| = | 24 | × | 1 2 |
| = | 12 | × | 1 |
| x | = | 12 |