( | 200 | + | 5 | x | ) | ( | 50 | − | x | ) | = | 10125 |
方程左边 = | 200 | ( | 50 | − | x | ) | + | 5 | x | ( | 50 | − | x | ) |
= | 200 | × | 50 | − | 200 | x | + | 5 | x | ( | 50 | − | x | ) |
= | 10000 | − | 200 | x | + | 5 | x | ( | 50 | − | x | ) |
= | 10000 | − | 200 | x | + | 5 | x | × | 50 | − | 5 | x | x |
= | 10000 | − | 200 | x | + | 250 | x | − | 5 | x | x |
= | 10000 | + | 50 | x | − | 5 | x | x |
10000 | + | 50 | x | − | 5 | x | x | = | 10125 |