400 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | = | 676 |
方程左边 = | 400 | × | 1 | ( | 1 | + | x | ) | + | 400 | x | ( | 1 | + | x | ) |
= | 400 | ( | 1 | + | x | ) | + | 400 | x | ( | 1 | + | x | ) |
= | 400 | × | 1 | + | 400 | x | + | 400 | x | ( | 1 | + | x | ) |
= | 400 | + | 400 | x | + | 400 | x | ( | 1 | + | x | ) |
= | 400 | + | 400 | x | + | 400 | x | × | 1 | + | 400 | x | x |
= | 400 | + | 400 | x | + | 400 | x | + | 400 | x | x |
= | 400 | + | 800 | x | + | 400 | x | x |
400 | + | 800 | x | + | 400 | x | x | = | 676 |
x1= | - | 23 10 |
x2= | 3 10 |