static void Main(string[] args) { var dathuc_1 = new DaThuc(3); dathuc_1.NhapDaThuc(); dathuc_1.XuatDaThuc(); var dathuc_2 = new DaThuc(3); dathuc_2.NhapDaThuc(); dathuc_2.XuatDaThuc(); Console.WriteLine(); Console.WriteLine("Da thuc 1 + Da thuc 2 = "); var dathuc_tong = dathuc_1 + dathuc_2; dathuc_tong.XuatDaThuc(); var tong_2 = dathuc_1.Cong(dathuc_2); tong_2.XuatDaThuc(); Console.WriteLine(); Console.WriteLine("Da thuc 1 - Da thuc 2 = "); var dathuc_hieu = dathuc_1 - dathuc_2; dathuc_hieu.XuatDaThuc(); var hieu_2 = dathuc_1.Tru(dathuc_2); hieu_2.XuatDaThuc(); Console.ReadLine(); }