B ^ 2 + C ^ 2 + 2Ab + 2Ac + 2BC factorization

B ^ 2 + C ^ 2 + 2Ab + 2Ac + 2BC factorization

b^2+c^2+2bc+2ab+2ac=(b+c)^2 +2a(b+c)=(b+c)(b+c+2a)