| ( | 3 | + | x | − | 2 | ) | ( | 500 | − | 100 | x | ) | = | 675 |
| 方程左边 = | 3 | ( | 500 | − | 100 | x | ) | + | x | ( | 500 | − | 100 | x | ) | − | 2 | ( | 500 | − | 100 | x | ) |
| = | 3 | × | 500 | − | 3 | × | 100 | x | + | x | ( | 500 | − | 100 | x | ) | − | 2 | ( | 500 | − | 100 | x | ) |
| = | 1500 | − | 300 | x | + | x | ( | 500 | − | 100 | x | ) | − | 2 | ( | 500 | − | 100 | x | ) |
| = | 1500 | − | 300 | x | + | x | × | 500 | − | x | × | 100 | x | − | 2 | ( | 500 | − | 100 | x | ) |
| = | 1500 | + | 200 | x | − | x | × | 100 | x | − | 2 | ( | 500 | − | 100 | x | ) |
| = | 1500 | + | 200 | x | − | x | × | 100 | x | − | 2 | × | 500 | + | 2 | × | 100 | x |
| = | 1500 | + | 200 | x | − | x | × | 100 | x | − | 1000 | + | 200 | x |
| = | 500 | + | 400 | x | − | x | × | 100 | x |
| 500 | + | 400 | x | − | x | × | 100 | x | = | 675 |
| x1= | 1 2 |
| x2= | 7 2 |