| ( | 10 | x | + | 2 | ) | ( | 100 | − | 4 | x | ) | = | 0 |
| 方程左边 = | 10 | x | ( | 100 | − | 4 | x | ) | + | 2 | ( | 100 | − | 4 | x | ) |
| = | 10 | x | × | 100 | − | 10 | x | × | 4 | x | + | 2 | ( | 100 | − | 4 | x | ) |
| = | 1000 | x | − | 40 | x | x | + | 2 | ( | 100 | − | 4 | x | ) |
| = | 1000 | x | − | 40 | x | x | + | 2 | × | 100 | − | 2 | × | 4 | x |
| = | 1000 | x | − | 40 | x | x | + | 200 | − | 8 | x |
| = | 992 | x | − | 40 | x | x | + | 200 |
| 992 | x | − | 40 | x | x | + | 200 | = | 0 |
| x1= | - | 1 5 |
| x2=25 |