reserve z,z1,z2,z3,z4 for Element of F_Complex;

theorem
  (-z)*' = -(z*')
proof
  reconsider z9=z as Element of COMPLEX by Def1;
  -z = -z9 by Th2;
  hence (-z)*' = -(z9*') by COMPLEX1:33
    .= -(z*') by Th2;
end;
