( | 80 | − | x | − | 50 | ) | ( | 10 | x | + | 200 | ) | = | 9000 |
方程左边 = | 80 | ( | 10 | x | + | 200 | ) | − | x | ( | 10 | x | + | 200 | ) | − | 50 | ( | 10 | x | + | 200 | ) |
= | 80 | × | 10 | x | + | 80 | × | 200 | − | x | ( | 10 | x | + | 200 | ) | − | 50 | ( | 10 | x | + | 200 | ) |
= | 800 | x | + | 16000 | − | x | ( | 10 | x | + | 200 | ) | − | 50 | ( | 10 | x | + | 200 | ) |
= | 800 | x | + | 16000 | − | x | × | 10 | x | − | x | × | 200 | − | 50 | ( | 10 | x | + | 200 | ) |
= | 600 | x | + | 16000 | − | x | × | 10 | x | − | 50 | ( | 10 | x | + | 200 | ) |
= | 600 | x | + | 16000 | − | x | × | 10 | x | − | 50 | × | 10 | x | − | 50 | × | 200 |
= | 600 | x | + | 16000 | − | x | × | 10 | x | − | 500 | x | − | 10000 |
= | 100 | x | + | 6000 | − | x | × | 10 | x |
100 | x | + | 6000 | − | x | × | 10 | x | = | 9000 |