| 15000 | ( | 1 | + | i | ) | ( | i | + | 49 50 | ) | = | 17820 |
| 方程左边 = | 15000 | × | 1 | ( | i | + | 49 50 | ) | + | 15000 | i | ( | i | + | 49 50 | ) |
| = | 15000 | ( | i | + | 49 50 | ) | + | 15000 | i | ( | i | + | 49 50 | ) |
| = | 15000 | i | + | 15000 | × | 49 50 | + | 15000 | i | ( | i | + | 49 50 | ) |
| = | 15000 | i | + | 14700 | + | 15000 | i | ( | i | + | 49 50 | ) |
| = | 15000 | i | + | 14700 | + | 15000 | i | i | + | 15000 | i | × | 49 50 |
| = | 15000 | i | + | 14700 | + | 15000 | i | i | + | 14700 | i |
| = | 29700 | i | + | 14700 | + | 15000 | i | i |
| 29700 | i | + | 14700 | + | 15000 | i | i | = | 17820 |
| i1= | - | 52 25 |
| i2= | 1 10 |