thắc mắc Trợ giúp winform C#

namespace HideForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            Form2 frm = new Form2(this);
            frm.Show();
            this.Hide();
        }
    }
}

namespace HideForm
{
    public partial class Form2 : Form
    {
        Form _hiddenform;
        public Form2(Form hiddenform)
        {
            _hiddenform = hiddenform;
            InitializeComponent();
        }

        private void Form2_FormClosing(object sender, FormClosingEventArgs e)
        {
            _hiddenform.Show();
        }
    }
}