reserve x, y, z, r, s, t for Real;

theorem
  x <> 0 implies |.x.| * |.1/x.| = 1
proof
  assume x <> 0;
  then |.x.| * |.1/x.| = |.x * (1/x).| & |.x * (1/x).| = |.1.|
  by COMPLEX1:65,XCMPLX_1:106;
  hence thesis;
end;
