If, x+1y=1 and y−1z=1, then the value of xyz is
If x, y and z are all different from zero and ∣∣ ∣∣1+x1111+y1111+z∣∣ ∣∣=0, then the value of x−1+y−1+z−1 is
(a) xyz (b) x−1y−1z−1 (c) −x−y−z (d) −1