( | 25 | − | 2 | x | ) | ( | 40 | − | 2 | x | ) | = | 450 |
方程左边 = | 25 | ( | 40 | − | 2 | x | ) | − | 2 | x | ( | 40 | − | 2 | x | ) |
= | 25 | × | 40 | − | 25 | × | 2 | x | − | 2 | x | ( | 40 | − | 2 | x | ) |
= | 1000 | − | 50 | x | − | 2 | x | ( | 40 | − | 2 | x | ) |
= | 1000 | − | 50 | x | − | 2 | x | × | 40 | + | 2 | x | × | 2 | x |
= | 1000 | − | 50 | x | − | 80 | x | + | 4 | x | x |
= | 1000 | − | 130 | x | + | 4 | x | x |
1000 | − | 130 | x | + | 4 | x | x | = | 450 |
x2= | 55 2 |