| ( | x | + | 7 10 | ) | ( | x | + | 7 10 | ) | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) | = | 25 4 |
| 方程左边 = | x | ( | x | + | 7 10 | ) | + | 7 10 | ( | x | + | 7 10 | ) | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) |
| = | x | x | + | x | × | 7 10 | + | 7 10 | ( | x | + | 7 10 | ) | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 10 | x | + | 7 10 | x | + | 7 10 | × | 7 10 | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 10 | x | + | 7 10 | x | + | 49 100 | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 5 | x | + | 49 100 | + | ( | 12 5 | − | x | ) | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 5 | x | + | 49 100 | + | 12 5 | ( | 12 5 | − | x | ) | − | x | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 5 | x | + | 49 100 | + | 12 5 | × | 12 5 | − | 12 5 | x | − | x | ( | 12 5 | − | x | ) |
| = | x | x | + | 7 5 | x | + | 49 100 | + | 144 25 | − | 12 5 | x | − | x | ( | 12 5 | − | x | ) |
| = | x | x | − | 1 | x | + | 25 4 | − | x | ( | 12 5 | − | x | ) |
| = | x | x | − | 1 | x | + | 25 4 | − | x | × | 12 5 | + | x | x |
| = | x | x | − | 17 5 | x | + | 25 4 | + | x | x |
| x | x | − | 17 5 | x | + | 25 4 | + | x | x | = | 25 4 |
| x2= | 17 10 |