Question

Factories:4-(x+y)²

Answer 1

In the given expression above we should factorize using this identity:

a2−b2=(a−b)(a+b)

4−(x+y)2
22−(x+y)2

=(2−(x+y))(2+(x+y))
=(2−x−y)(2+x+y)

There are two factors:
2−x−y and 2+x+y