x | − | ( | ( | x | − | 5000 | ) | × | 1 10 | − | 210 | ) | = | 12500 |
方程左边 = | x | − | ( | x | − | 5000 | ) | × | 1 10 | + | 210 |
= | x | − | x | × | 1 10 | + | 5000 | × | 1 10 | + | 210 |
= | x | − | x | × | 1 10 | + | 500 | + | 210 |
= | 9 10 | x | + | 710 |
9 10 | x | + | 710 | = | 12500 |
9 10 | x | = | 12500 | − | 710 |
9 10 | x | = | 11790 |
x | = | 11790 | ÷ | 9 10 |
= | 11790 | × | 10 9 |
= | 1310 | × | 10 |
x | = | 13100 |