( | X | − | 20 | ) | ( | - | 10 | X | − | 1540 | ) | = | 0 |
方程左边 = | X | ( | - | 10 | X | − | 1540 | ) | − | 20 | ( | - | 10 | X | − | 1540 | ) |
= | - | X | × | 10 | X | − | X | × | 1540 | − | 20 | ( | - | 10 | X | − | 1540 | ) |
= | - | X | × | 10 | X | − | 1540 | X | + | 20 | × | 10 | X | + | 20 | × | 1540 |
= | - | X | × | 10 | X | − | 1540 | X | + | 200 | X | + | 30800 |
= | - | X | × | 10 | X | − | 1340 | X | + | 30800 |
- | X | × | 10 | X | − | 1340 | X | + | 30800 | = | 0 |