20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | − | 20 | ( | 1 | + | x | ) | = | 24 5 |
方程左边 = | 20 | × | 1 | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) | − | 20 | ( | 1 | + | x | ) |
= | 20 | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) | − | 20 | ( | 1 | + | x | ) |
= | 20 | × | 1 | + | 20 | x | + | 20 | x | ( | 1 | + | x | ) | − | 20 | ( | 1 | + | x | ) |
= | 20 | + | 20 | x | + | 20 | x | ( | 1 | + | x | ) | − | 20 | ( | 1 | + | x | ) |
= | 20 | + | 20 | x | + | 20 | x | × | 1 | + | 20 | x | x | − | 20 | ( | 1 | + | x | ) |
= | 20 | + | 20 | x | + | 20 | x | + | 20 | x | x | − | 20 | ( | 1 | + | x | ) |
= | 20 | + | 40 | x | + | 20 | x | x | − | 20 | ( | 1 | + | x | ) |
= | 20 | + | 40 | x | + | 20 | x | x | − | 20 | × | 1 | − | 20 | x |
= | 20 | + | 40 | x | + | 20 | x | x | − | 20 | − | 20 | x |
= | 0 | + | 20 | x | + | 20 | x | x |
20 | x | + | 20 | x | x | = | 24 5 |
x1= | - | 6 5 |
x2= | 1 5 |