[질문] (a+b)(a+b)

(a+b)(a+b) can be expanded using the distributive property:

(a+b)(a+b) = a(a+b) + b(a+b)

Using the distributive property again:

= a^2 + ab + ba + b^2

Since multiplication is commutative, ab and ba are the same:

= a^2 + 2ab + b^2

So, (a+b)(a+b) = a^2 + 2ab + b^2.