| ( | 2 | m | + | 7 | ) | ( | 1 | − | 4 | m | ) | = | 0 |
| Left side of the equation = | 2 | m | ( | 1 | − | 4 | m | ) | + | 7 | ( | 1 | − | 4 | m | ) |
| = | 2 | m | × | 1 | − | 2 | m | × | 4 | m | + | 7 | ( | 1 | − | 4 | m | ) |
| = | 2 | m | − | 8 | m | m | + | 7 | ( | 1 | − | 4 | m | ) |
| = | 2 | m | − | 8 | m | m | + | 7 | × | 1 | − | 7 | × | 4 | m |
| = | 2 | m | − | 8 | m | m | + | 7 | − | 28 | m |
| = | - | 26 | m | − | 8 | m | m | + | 7 |
| - | 26 | m | − | 8 | m | m | + | 7 | = | 0 |
| m1= | - | 7 2 |
| m2= | 1 4 |