20 | ( | x | − | 1 | ) | + | 30 | ( | x | + | 1 | − | 3 2 | ) | = | 90 |
方程左边 = | 20 | x | − | 20 | × | 1 | + | 30 | ( | x | + | 1 | − | 3 2 | ) |
= | 20 | x | − | 20 | + | 30 | ( | x | + | 1 | − | 3 2 | ) |
= | 20 | x | − | 20 | + | 30 | x | + | 30 | × | 1 | − | 30 | × | 3 2 |
= | 20 | x | − | 20 | + | 30 | x | + | 30 | − | 45 |
= | 50 | x | − | 35 |
50 | x | − | 35 | = | 90 |
50 | x | = | 90 | + | 35 |
50 | x | = | 125 |
x | = | 125 | ÷ | 50 |
= | 125 | × | 1 50 |
= | 5 | × | 1 2 |
x | = | 5 2 |
x | = | 2.5 |