| ( | 3 | − | 5 | x | ) | ( | 3 | − | 5 | x | ) | = | 9 | x | x | + | 3 | x | x |
| Left side of the equation = | 3 | ( | 3 | − | 5 | x | ) | − | 5 | x | ( | 3 | − | 5 | x | ) |
| = | 3 | × | 3 | − | 3 | × | 5 | x | − | 5 | x | ( | 3 | − | 5 | x | ) |
| = | 9 | − | 15 | x | − | 5 | x | ( | 3 | − | 5 | x | ) |
| = | 9 | − | 15 | x | − | 5 | x | × | 3 | + | 5 | x | × | 5 | x |
| = | 9 | − | 15 | x | − | 15 | x | + | 25 | x | x |
| = | 9 | − | 30 | x | + | 25 | x | x |
| 9 | − | 30 | x | + | 25 | x | x | = | 9 | x | x | + | 3 | x | x |