(a+b+c)2(a+b+c)^2(a+b+c)2 =(a+b+c)⋅(a+b+c) = (a+b+c) \cdot (a+b+c)=(a+b+c)⋅(a+b+c) =a2+ab+ac+b2+ab+bc+c2+ac+bc = a^2 + ab + ac + b^2 + ab + bc + c^2 + ac + bc=a2+ab+ac+b2+ab+bc+c2+ac+bc =a2+b2+c2+2ab+2ac+2bc= a^2 + b^2 + c^2 + 2ab + 2ac + 2bc=a2+b2+c2+2ab+2ac+2bc
