19 20 | ( | 400 | + | 400 | ( | 1 | + | x | ) | + | 400 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ) | = | 2000 |
方程左边 = | 19 20 | × | 400 | + | 19 20 | × | 400 | ( | 1 | + | x | ) | + | 19 20 | × | 400 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
= | 380 | + | 380 | ( | 1 | + | x | ) | + | 380 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
= | 380 | + | 380 | × | 1 | + | 380 | x | + | 380 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
= | 380 | + | 380 | + | 380 | x | + | 380 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
= | 760 | + | 380 | x | + | 380 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
= | 760 | + | 380 | x | + | 380 | × | 1 | ( | 1 | + | x | ) | + | 380 | x | ( | 1 | + | x | ) |
= | 760 | + | 380 | x | + | 380 | ( | 1 | + | x | ) | + | 380 | x | ( | 1 | + | x | ) |
= | 760 | + | 380 | x | + | 380 | × | 1 | + | 380 | x | + | 380 | x | ( | 1 | + | x | ) |
= | 760 | + | 380 | x | + | 380 | + | 380 | x | + | 380 | x | ( | 1 | + | x | ) |
= | 1140 | + | 760 | x | + | 380 | x | ( | 1 | + | x | ) |
= | 1140 | + | 760 | x | + | 380 | x | × | 1 | + | 380 | x | x |
= | 1140 | + | 760 | x | + | 380 | x | + | 380 | x | x |
= | 1140 | + | 1140 | x | + | 380 | x | x |
1140 | + | 1140 | x | + | 380 | x | x | = | 2000 |