| ( | s | + | 1 | ) | ( | 2 | s | + | 1 | ) | ( | 4 | s | + | 1 | ) | + | 20 | = | 0 |
| 方程左边 = | s | ( | 2 | s | + | 1 | ) | ( | 4 | s | + | 1 | ) | + | 1 | ( | 2 | s | + | 1 | ) | ( | 4 | s | + | 1 | ) | + | 20 |
| = | s | × | 2 | s | ( | 4 | s | + | 1 | ) | + | s | × | 1 | ( | 4 | s | + | 1 | ) | + | 1 | ( | 2 | s | + | 1 | ) | ( | 4 | s | + | 1 | ) | + | 20 |
| = | s | × | 2 | s | × | 4 | s | + | s | × | 2 | s | × | 1 | + | s | × | 1 | ( | 4 | s | + | 1 | ) |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 1 | ( | 4 | s | + | 1 | ) | + | 1 | ( | 2 | s | + | 1 | ) |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 1 | × | 4 | s | + | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | s | × | 1 |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 1 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 1 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 1 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 1 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 3 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 3 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 3 | s |
| = | s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 7 | s |
| s | × | 8 | s | s | + | s | × | 2 | s | + | s | × | 4 | s | + | 7 | s | = | 0 |