| ( | a | × | 2 | − | 5 | a | + | 4 | ) | × | 2 | = | 8 | ( | a | − | 4 | ) | × | 2 |
| 方程左边 = | a | × | 2 | × | 2 | − | 5 | a | × | 2 | + | 4 | × | 2 |
| = | a | × | 4 | − | 10 | a | + | 8 |
| = | - | 6 | a | + | 8 |
| - | 6 | a | + | 8 | = | 8 | ( | a | − | 4 | ) | × | 2 |
| 方程右边 = | 16 | ( | a | − | 4 | ) |
| - | 6 | a | + | 8 | = | 16 | ( | a | − | 4 | ) |
| 方程右边 = | 16 | a | − | 16 | × | 4 |
| = | 16 | a | − | 64 |
| - | 6 | a | + | 8 | = | 16 | a | − | 64 |
| - | 6 | a | − | 16 | a | = | - | 64 | − | 8 |
| - | 22 | a | = | - | 64 | − | 8 |
| - | 22 | a | = | - | 72 |
| 72 | = | 22 | a |
| 22 | a | = | 72 |
| a | = | 72 | ÷ | 22 |
| = | 72 | × | 1 22 |
| = | 36 | × | 1 11 |
| a | = | 36 11 |
| a | = | 3.272727 |