Question

Помогите!!!!!!!!!!!!!!!!!!!!!

Answer 1

a²+b²+c²=17   a-b-c=5   bc-ab-ac - ?
(a-b-c)²=5²
((a-b)-c)²=25
(a-b)²-2*(a-b)*c+c²=25
a²-2ab+b²-2ac+2bc+c²=25
(a²+b²+c²)+2*(bc-ab-ac)=25
17+2*(bc-ab-ac)=25
2*(bc-ab-ac)=8
bc-ab-ac=4.