| 2 | = | a | ( | 0 | − | 5 2 | ) | ( | 0 | + | 5 2 | ) |
| 方程右边 = | a | × | 0 | ( | 0 | + | 5 2 | ) | − | a | × | 5 2 | ( | 0 | + | 5 2 | ) |
| = | a | × | 0 | × | 0 | + | a | × | 0 | × | 5 2 | − | a | × | 5 2 | ( | 0 | + | 5 2 | ) |
| = | a | × | 0 | + | a | × | 0 | − | a | × | 5 2 | ( | 0 | + | 5 2 | ) |
| = | 0 | a | − | a | × | 5 2 | ( | 0 | + | 5 2 | ) |
| = | 0 | a | − | a | × | 5 2 | × | 0 | − | a | × | 5 2 | × | 5 2 |
| = | 0 | a | − | a | × | 0 | − | a | × | 25 4 |
| = | - | 25 4 | a |
| 2 | = | - | 25 4 | a |
25 4 | a | = | - | 2 |
| a | = | - | 2 | ÷ | 25 4 |
| = | - | 2 | × | 4 25 |
| a | = | - | 8 25 |
| a | = | - 0.32 |