Question

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

Answer 1

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