The document provides 3 examples of factorizing quadratic expressions. The first example factors (3x-1)(3x+1) into 9x^2-1. The second example factors (x+y)(x-y) into x^2-y^2. The third example factors (a^2-b)(a^2+b) into a^4-b^2.

5. EJEMPLO 1
(3x-1)(3x+1)=9x2-1

6. EJEMPLO 2
(x+ y)(x – y) = x2 – y2

7. EJEMPLO 3
(a2 – b)(a2 + b) = a4– b2