( | 35 | − | 2 | x | ) | ( | 20 | − | 2 | x | ) | = | 496 |
方程左边 = | 35 | ( | 20 | − | 2 | x | ) | − | 2 | x | ( | 20 | − | 2 | x | ) |
= | 35 | × | 20 | − | 35 | × | 2 | x | − | 2 | x | ( | 20 | − | 2 | x | ) |
= | 700 | − | 70 | x | − | 2 | x | ( | 20 | − | 2 | x | ) |
= | 700 | − | 70 | x | − | 2 | x | × | 20 | + | 2 | x | × | 2 | x |
= | 700 | − | 70 | x | − | 40 | x | + | 4 | x | x |
= | 700 | − | 110 | x | + | 4 | x | x |
700 | − | 110 | x | + | 4 | x | x | = | 496 |
x2= | 51 2 |