| 7 | ( | 2 | x | − | 1 | ) | − | 3 | ( | 4 | x | − | 1 | ) | − | 5 | ( | 3 | x | + | 2 | ) | + | 1 | = | 0 |
| Left side of the equation = | 7 | × | 2 | x | − | 7 | × | 1 | − | 3 | ( | 4 | x | − | 1 | ) | − | 5 | ( | 3 | x | + | 2 | ) | + | 1 |
| = | 14 | x | − | 7 | − | 3 | ( | 4 | x | − | 1 | ) | − | 5 | ( | 3 | x | + | 2 | ) | + | 1 |
| = | 14 | x | − | 6 | − | 3 | ( | 4 | x | − | 1 | ) | − | 5 | ( | 3 | x | + | 2 | ) |
| = | 14 | x | − | 6 | − | 3 | × | 4 | x | + | 3 | × | 1 | − | 5 | ( | 3 | x | + | 2 | ) |
| = | 14 | x | − | 6 | − | 12 | x | + | 3 | − | 5 | ( | 3 | x | + | 2 | ) |
| = | 2 | x | − | 3 | − | 5 | ( | 3 | x | + | 2 | ) |
| = | 2 | x | − | 3 | − | 5 | × | 3 | x | − | 5 | × | 2 |
| = | 2 | x | − | 3 | − | 15 | x | − | 10 |
| = | - | 13 | x | − | 13 |
| - | 13 | x | − | 13 | = | 0 |
| - | 13 | x | = | 0 | + | 13 |
| - | 13 | x | = | 13 |
| - | 13 | = | 13 | x |
| 13 | x | = | - | 13 |
| x | = | - | 13 | ÷ | 13 |
| = | - | 13 | × | 1 13 |
| = | - | 1 | × | 1 |
| x | = | - | 1 |