100 | × | 21 | + | x | × | 49 2 | = | ( | 100 | + | x | ) | × | 25 |
方程左边 = | 2100 | + | x | × | 49 2 |
2100 | + | 49 2 | x | = | ( | 100 | + | x | ) | × | 25 |
方程右边 = | 100 | × | 25 | + | x | × | 25 |
= | 2500 | + | x | × | 25 |
2100 | + | 49 2 | x | = | 2500 | + | 25 | x |
49 2 | x | − | 25 | x | = | 2500 | − | 2100 |
- | 1 2 | x | = | 2500 | − | 2100 |
- | 1 2 | x | = | 400 |
- | 400 | = | 1 2 | x |
1 2 | x | = | - | 400 |
x | = | - | 400 | ÷ | 1 2 |
= | - | 400 | × | 2 |
x | = | - | 800 |