7 | x | ( | 2 | x | − | 1 | ) | − | 3 | ( | 4 | x | − | 1 | ) | − | 2 | x | ( | x | + | 3 | ) | + | 1 | = | 0 |
方程左边 = | 7 | x | × | 2 | x | − | 7 | x | × | 1 | − | 3 | ( | 4 | x | − | 1 | ) | − | 2 | x | ( | x | + | 3 | ) |
= | 14 | x | x | − | 7 | x | − | 3 | ( | 4 | x | − | 1 | ) | − | 2 | x | ( | x | + | 3 | ) | + | 1 |
= | 14 | x | x | − | 7 | x | − | 3 | × | 4 | x | + | 3 | × | 1 | − | 2 | x |
= | 14 | x | x | − | 7 | x | − | 12 | x | + | 3 | − | 2 | x | ( | x | + | 3 | ) | + | 1 |
= | 14 | x | x | − | 19 | x | + | 4 | − | 2 | x | ( | x | + | 3 | ) |
= | 14 | x | x | − | 19 | x | + | 4 | − | 2 | x | x | − | 2 | x | × | 3 |
= | 14 | x | x | − | 19 | x | + | 4 | − | 2 | x | x | − | 6 | x |
= | 14 | x | x | − | 25 | x | + | 4 | − | 2 | x | x |
14 | x | x | − | 25 | x | + | 4 | − | 2 | x | x | = | 0 |