private void button1_Click(object sender, EventArgs e)
{
TaiKhoan taiKhoan = new TaiKhoan();
this.Hide();
taiKhoan.Show();
}
private void button5_Click(object sender, EventArgs e)
{
TaiKhoan tk = new TaiKhoan();
tk.TenTK = _tenTK;
tk.TenMK = _tenMK;
tk.Show();
}