| 7000 | = | 3000 | ( | 1 | − | x | ) | + | 4000 | ( | 1 | + | 2 | x | ) | ( | 1 | − | x | ) |
| Right side of the equation = | 3000 | × | 1 | − | 3000 | x | + | 4000 | ( | 1 | + | 2 | x | ) | ( | 1 | − | x | ) |
| = | 3000 | − | 3000 | x | + | 4000 | ( | 1 | + | 2 | x | ) | ( | 1 | − | x | ) |
| = | 3000 | − | 3000 | x | + | 4000 | × | 1 | ( | 1 | − | x | ) | + | 4000 | × | 2 | x | ( | 1 | − | x | ) |
| = | 3000 | − | 3000 | x | + | 4000 | ( | 1 | − | x | ) | + | 8000 | x | ( | 1 | − | x | ) |
| = | 3000 | − | 3000 | x | + | 4000 | × | 1 | − | 4000 | x | + | 8000 | x | ( | 1 | − | x | ) |
| = | 3000 | − | 3000 | x | + | 4000 | − | 4000 | x | + | 8000 | x | ( | 1 | − | x | ) |
| = | 7000 | − | 7000 | x | + | 8000 | x | ( | 1 | − | x | ) |
| = | 7000 | − | 7000 | x | + | 8000 | x | × | 1 | − | 8000 | x | x |
| = | 7000 | − | 7000 | x | + | 8000 | x | − | 8000 | x | x |
| = | 7000 | + | 1000 | x | − | 8000 | x | x |
| 7000 | = | 7000 | + | 1000 | x | − | 8000 | x | x |
| x2= | 1 8 |