| ( | ( | ( | 9 10 | + | 1 | ) | × | 9 10 | + | 1 | ) | × | 9 10 | + | x | ) | × | 21 20 | = | 3 | + | x |
| 方程左边 = | ( | ( | 9 10 | + | 1 | ) | × | 9 10 | + | 1 | ) | × | 9 10 | × | 21 20 | + | x | × | 21 20 |
| = | ( | ( | 9 10 | + | 1 | ) | × | 9 10 | + | 1 | ) | × | 189 200 | + | x | × | 21 20 |
| = | ( | 9 10 | + | 1 | ) | × | 9 10 | × | 189 200 | + | 1 | × | 189 200 | + | 21 20 | x |
| = | ( | 9 10 | + | 1 | ) | × | 1701 2000 | + | 189 200 | + | 21 20 | x |
| = | 9 10 | × | 1701 2000 | + | 1 | × | 1701 2000 | + | 189 200 | + | 21 20 | x |
| = | 15309 20000 | + | 1701 2000 | + | 189 200 | + | 21 20 | x |
| = | 51219 20000 | + | 21 20 | x |
51219 20000 | + | 21 20 | x | = | 3 | + | x |
21 20 | x | − | x | = | 3 | − | 51219 20000 |
1 20 | x | = | 3 | − | 51219 20000 |
1 20 | x | = | 8781 20000 |
| x | = | 8781 20000 | ÷ | 1 20 |
| = | 8781 20000 | × | 20 |
| = | 8781 1000 | × | 1 |
| x | = | 8781 1000 |
| x | = | 8.781 |