Given x+a=y+b=z+c+1
Now ∣xyza+yb+yc+ya+xb+yc+z∣=∣xyza+yb+yc+yabc∣(C3→C3−C1)
=∣xyzyyyabc∣(C2→C2−C3)
=y∣xyz111abc∣
R2→R2−R1 and R3→R3−R1
y∣xy−xz−x100ab−ac−a∣=y∣xa−bz−x100a−(a−b)c−a∣=y(a−b)∣x1z−x100a−1c−a∣=−y(a−b)(c−a+z−x)=y(a−b)