Question

(х+у+z)в квадрате
(а-(в-с))в квадрате(

Answer 1

(x+y+z)²=(x+y)²+2(x+y)z+z²=x²+2xy+y²+2xz+2yx+z²
(a-(b-c))²=a²-2a(b-c)+(b-c)²=a²-2ab+2ac+b²-2bc+c²