81 100 | ( | x | + | 2 5 | ) | ( | x | + | 2 5 | ) | = | 144 | x |
| 方程左边 = | 81 100 | x | ( | x | + | 2 5 | ) | + | 81 100 | × | 2 5 | ( | x | + | 2 5 | ) |
| = | 81 100 | x | ( | x | + | 2 5 | ) | + | 81 250 | ( | x | + | 2 5 | ) |
| = | 81 100 | x | x | + | 81 100 | x | × | 2 5 | + | 81 250 | ( | x | + | 2 5 | ) |
| = | 81 100 | x | x | + | 81 250 | x | + | 81 250 | ( | x | + | 2 5 | ) |
| = | 81 100 | x | x | + | 81 250 | x | + | 81 250 | x | + | 81 250 | × | 2 5 |
| = | 81 100 | x | x | + | 81 250 | x | + | 81 250 | x | + | 81 625 |
| = | 81 100 | x | x | + | 81 125 | x | + | 81 625 |
81 100 | x | x | + | 81 125 | x | + | 81 625 | = | 144 | x |