| ( | 1721 | + | x | ) | ÷ | ( | 1965 | + | x | ) | = | 9 10 |
| 方程两边同时乘以: | ( | 1965 | + | x | ) |
| ( | 1721 | + | x | ) | = | 9 10 | ( | 1965 | + | x | ) |
| 1721 | + | x | = | 9 10 | ( | 1965 | + | x | ) |
| 1721 | + | x | = | 9 10 | × | 1965 | + | 9 10 | x |
| 1721 | + | x | = | 3537 2 | + | 9 10 | x |
| x | − | 9 10 | x | = | 3537 2 | − | 1721 |
1 10 | x | = | 3537 2 | − | 1721 |
1 10 | x | = | 95 2 |
| x | = | 95 2 | ÷ | 1 10 |
| = | 95 2 | × | 10 |
| = | 95 | × | 5 |
| x | = | 475 |