Question

Prove that (a+b)^2=a2 +b2+2ab

Answer 1

(a+b)(a+b)
= a(a+b) + b(a+b)
= a²+ab+ab+b²
= a²+2ab+b²

hence proved

Answer 2

Suppose (a+b)^2 = (a+b)(a+b)

                by multiplication,

                (a+b) * (a+b) = a2 +ab + ba + b2 

                                     = a2+ 2ab + b2

hence proved