| ( | 4 | − | a | ) | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) | = | 0 |
| 方程左边 = | 4 | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 4 | × | 10 | ( | 4 | − | a | ) | − | 4 | a | ( | 4 | − | a | ) | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 40 | ( | 4 | − | a | ) | − | 4 | a | ( | 4 | − | a | ) | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 40 | × | 4 | − | 40 | a | − | 4 | a | ( | 4 | − | a | ) | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 160 | − | 40 | a | − | 4 | a | ( | 4 | − | a | ) | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 160 | − | 40 | a | − | 4 | a | × | 4 | + | 4 | a | a | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) |
| = | 160 | − | 40 | a | − | 16 | a | + | 4 | a | a | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 160 | − | 56 | a | + | 4 | a | a | − | a | ( | 10 | − | a | ) | ( | 4 | − | a | ) | − | ( | 10 | − | a | ) |
| = | 160 | − | 56 | a | + | 4 | a | a | − | a | × | 10 | ( | 4 | − | a | ) | + | a | a | ( | 4 | − | a | ) |
| = | 160 | − | 56 | a | + | 4 | a | a | − | a | × | 10 | × | 4 | + | a | × | 10 | a |
| = | 160 | − | 56 | a | + | 4 | a | a | − | a | × | 40 | + | a | × | 10 | a | + | a |
| = | 160 | − | 96 | a | + | 4 | a | a | + | a | × | 10 | a | + | a | a | ( | 4 | − | a | ) |
| = | 160 | − | 96 | a | + | 4 | a | a | + | a | × | 10 | a | + | a | a | × | 4 |
| = | 160 | − | 96 | a | + | 4 | a | a | + | a | × | 10 | a | + | a | a | × | 4 |
| = | 150 | − | 95 | a | + | 4 | a | a | + | a | × | 10 | a | + | a | a | × | 4 |
| 150 | − | 95 | a | + | 4 | a | a | + | a | × | 10 | a | + | a | a | × | 4 | = | 0 |