Question

піднести до квадрата (b+c-a)^2=

Answer 1

$(b+c-a)^2=(\, (b+c)-a\, )^2=(b+c)^2-2a(b+c)+a^2=\\\\=b^2+2bc+c^2-2ab-2ac+a^2=\\\\=a^2+b^2+c^2-2ab-2ac+2bc$

Answer 2

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