| 1200 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | = | 1452 |
| Left side of the equation = | 1200 | × | 1 | ( | 1 | + | x | ) | + | 1200 | x | ( | 1 | + | x | ) |
| = | 1200 | ( | 1 | + | x | ) | + | 1200 | x | ( | 1 | + | x | ) |
| = | 1200 | × | 1 | + | 1200 | x | + | 1200 | x | ( | 1 | + | x | ) |
| = | 1200 | + | 1200 | x | + | 1200 | x | ( | 1 | + | x | ) |
| = | 1200 | + | 1200 | x | + | 1200 | x | × | 1 | + | 1200 | x | x |
| = | 1200 | + | 1200 | x | + | 1200 | x | + | 1200 | x | x |
| = | 1200 | + | 2400 | x | + | 1200 | x | x |
| 1200 | + | 2400 | x | + | 1200 | x | x | = | 1452 |
| x1= | - | 21 10 |
| x2= | 1 10 |