(xbxc)(b+c−a).(xcxa)(c+a−b).(xaxb)(a+b−c)=?
1
On multiplying the powers and adding them,
(b-c)(b+c-a) + (c-a)(c+a-b) + (a-b)(a+b-c)
= b2+bc-ab-bc-c2+ac +c2+ac-bc-ac-a2+ab +a2+ab-ac-ab-b2+bc
= 0
So, x(b−c)(b+c−a)+(c−a)(c+a−b)+(a−b)(a+b−c) = x0 = 1