reserve a, a9, a1, a2, a3, b, b9, c, c9, d, d9, h, p, q, x, x1, x2, x3, u, v,
  y, z for Real;

theorem
  for b, c being Complex holds b <> 0 & (for x being Real
  holds Polynom(0,b,c,x) = 0) implies x = -(c/b)
proof
  let b, c be Complex;
  assume
A1: b <> 0;
  set y = x;
  assume for x being Real holds Polynom(0,b,c,x) = 0;
  then Polynom(0,b,c,y) = 0;
  then y = (-c)/b by A1,XCMPLX_1:89
    .= ((-1)*c)*b" by XCMPLX_0:def 9
    .= (-1)*(c*b")
    .= (-1)*(c/b) by XCMPLX_0:def 9;
  hence thesis;
end;
