( | 121 | + | x | ) | ( | 300 | − | 2 | x | ) | − | 10 | x | − | ( | 300 | − | 2 | x | ) | × | 31 | = | 28200 |
方程左边 = | 121 | ( | 300 | − | 2 | x | ) | + | x | ( | 300 | − | 2 | x | ) | − | 10 | x | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 121 | × | 300 | − | 121 | × | 2 | x | + | x | ( | 300 | − | 2 | x | ) | − | 10 | x | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 36300 | − | 242 | x | + | x | ( | 300 | − | 2 | x | ) | − | 10 | x | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 36300 | − | 252 | x | + | x | ( | 300 | − | 2 | x | ) | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 36300 | − | 252 | x | + | x | × | 300 | − | x | × | 2 | x | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 36300 | + | 48 | x | − | x | × | 2 | x | − | ( | 300 | − | 2 | x | ) | × | 31 |
= | 36300 | + | 48 | x | − | x | × | 2 | x | − | 300 | × | 31 | + | 2 | x | × | 31 |
= | 36300 | + | 48 | x | − | x | × | 2 | x | − | 9300 | + | 62 | x |
= | 27000 | + | 110 | x | − | x | × | 2 | x |
27000 | + | 110 | x | − | x | × | 2 | x | = | 28200 |