( | - | 1 | + | 7 | x | ) | ( | - | 1 | + | 7 | x | ) | = | 0 |
方程左边 = | - | 1 | ( | - | 1 | + | 7 | x | ) | + | 7 | x | ( | - | 1 | + | 7 | x | ) |
= | 1 | × | 1 | − | 1 | × | 7 | x | + | 7 | x | ( | - | 1 | + | 7 | x | ) |
= | 1 | − | 7 | x | + | 7 | x | ( | - | 1 | + | 7 | x | ) |
= | 1 | − | 7 | x | − | 7 | x | × | 1 | + | 7 | x | × | 7 | x |
= | 1 | − | 7 | x | − | 7 | x | + | 49 | x | x |
= | 1 | − | 14 | x | + | 49 | x | x |
1 | − | 14 | x | + | 49 | x | x | = | 0 |
x1= | 1 7 |
x2= | 1 7 |