Let
Δ=a−b and p−q and x−yb−c and q−r and y−zc−a and r−p and z−xApplying the row operation
R1→R1+R2+R3, we get:
Δ=(a−b)+(b−c)+(c−a) and (p−q)+(q−r)+(r−p) and (x−y)+(y−z)+(z−x)b−c and q−r and y−zc−a and r−p and z−xΔ=0 and 0 and 0b−c and q−r and y−zc−a and r−p and z−xSince all elements of the first row are zero, the value of the determinant is
0.
Comparing this with
ka and b and cp and q and rx and y and z, we get
k=0.