( | 200 | − | x | − | 155 | ) | ( | 20 | + | 2 | x | ) | = | 0 |
方程左边 = | 200 | ( | 20 | + | 2 | x | ) | − | x | ( | 20 | + | 2 | x | ) | − | 155 | ( | 20 | + | 2 | x | ) |
= | 200 | × | 20 | + | 200 | × | 2 | x | − | x | ( | 20 | + | 2 | x | ) | − | 155 | ( | 20 | + | 2 | x | ) |
= | 4000 | + | 400 | x | − | x | ( | 20 | + | 2 | x | ) | − | 155 | ( | 20 | + | 2 | x | ) |
= | 4000 | + | 400 | x | − | x | × | 20 | − | x | × | 2 | x | − | 155 | ( | 20 | + | 2 | x | ) |
= | 4000 | + | 380 | x | − | x | × | 2 | x | − | 155 | ( | 20 | + | 2 | x | ) |
= | 4000 | + | 380 | x | − | x | × | 2 | x | − | 155 | × | 20 | − | 155 | × | 2 | x |
= | 4000 | + | 380 | x | − | x | × | 2 | x | − | 3100 | − | 310 | x |
= | 900 | + | 70 | x | − | x | × | 2 | x |
900 | + | 70 | x | − | x | × | 2 | x | = | 0 |