( | 40 | + | 2 | x | ) | ( | 3020 | − | 20 | x | ) | = | 0 |
方程左边 = | 40 | ( | 3020 | − | 20 | x | ) | + | 2 | x | ( | 3020 | − | 20 | x | ) |
= | 40 | × | 3020 | − | 40 | × | 20 | x | + | 2 | x | ( | 3020 | − | 20 | x | ) |
= | 120800 | − | 800 | x | + | 2 | x | ( | 3020 | − | 20 | x | ) |
= | 120800 | − | 800 | x | + | 2 | x | × | 3020 | − | 2 | x | × | 20 | x |
= | 120800 | − | 800 | x | + | 6040 | x | − | 40 | x | x |
= | 120800 | + | 5240 | x | − | 40 | x | x |
120800 | + | 5240 | x | − | 40 | x | x | = | 0 |