s | ( | 7 100 | ( | 1 | − | 7 100 | ) | × | 15 100 | ) | = | 0 |
方程左边 = | s | × | 7 100 | ( | 1 | − | 7 100 | ) | × | 15 100 |
= | s | × | 21 2000 | ( | 1 | − | 7 100 | ) |
= | s | × | 21 2000 | × | 1 | − | s | × | 21 2000 | × | 7 100 |
= | s | × | 21 2000 | − | s | × | 147 200000 |
= | 1953 200000 | s |
1953 200000 | s | = | 0 |
s | = | 0 | ÷ | 1953 200000 |
= | 0 | × | 200000 1953 |
s | = | 0 |