Question

1-а(а-в-с)+в(а-в+с)+с(в-а-с)

Answer 1

$1-a(a-b-c)+b(a-b+c)+c(b-a-c)= \ =1-a^2+ab+ac+ab-b^2+bc+bc-ac-c^2= \ =1-a^2+2ab-b^2+2bc-c^2$