Quadratic Expansion − Difference of two Squares
When expanding (x + 2)(x − 2) it gives x2 − 22 because the x terms cancel out
Example 1. Expand (x + 3)(x − 3)
Example 2. Expand (x − 5)(x + 5)
(x + 3)(x − 3)
| = x2 − 3x + 3x − 9 | |
| = x2 − 9 |
(x − 5)(x + 5)
| = x2 + 5x − 5x − 25 | |
| = x2 − 25 |
to: 
