(A+B) whole square

Question

(a + b)² = 

Answer 1

Taking LHS of the identity: 
(a + b)² 

This can also be written as: 
= (a + b) (a + b) 

Multiply as we do multiplication of two binomials and we get: 
= a(a + b) + b(a + b) 
= a² + ab + ab + b² 

Add like terms and we get: 
= a² + 2ab + b² 

Rearrange the terms and we get: 
= a² + b² + 2ab 

Hence, in this way we obtain the identity i.e. (a + b)² = a² + b² + 2ab

Answer 2

A^{​​​​​​2}+B^{​​​​​​2}+2AB