Factorisation Using Special Algebraic Identities (Chap 4.3)

Factorisation Using Special Algebraic Identities 

Since factorisation is the reverse of expansion, we have:

  a² + 2ab + b² = (a + b)²

a² - 2ab + b² = (a - b)²

                                                  a² - b² = (a + b)(a - b)

a) 4x² - 25y² = (2x)² - (5y)² 

= (2x + 5y)(2x - 5y)  

 (apply a² - b² = (a + b)(a - b), where a = 2x and b= 5y)