Question

Factorise the following expression.

y² − 4

Answer 1

y² − 4

Let us identify a and b as the difference of squares.

a = y²

b = 2² = 4 

= (y)² − (2)²

a² − b² = (a + b) (a − b)

(y)² − (2)² = (y + 2) (y − 2)