---

procedure TForm1.Button1Click(Sender: TObject);
Var x, y:real;
begin
  x := StrToFloat(Edit1.Text);
  y := StrToFloat(Edit2.Text);
  if (x >= -1) and (x <= 3) and (y >= -2) and (y <= 4) then
  checkbox1.state := cbchecked
  else checkbox2.state := cbchecked;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  edit1.Clear;
  edit2.Clear;
  edit1.Setfocus;
  checkbox1.State := cbunchecked;
  checkbox2.State := cbunchecked;
end;