C#求一元二次方程的根

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 求一元二次方程的根
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private double[] Root2(double a, double b, double c)
        {
            double []Roots=new double[2];
            double Delt=b * b - 4 * a * c;
            if (Delt >= 0)
            {
                Roots[0] = (-b + Math.Sqrt(Delt)) / 2 * a;
                Roots[1] = (-b - Math.Sqrt(Delt)) / 2 * a;
                return Roots;
            }
            else
            {
                Roots = null;
                return Roots;
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (Root2(double.Parse(textBox1.Text), double.Parse(textBox2.Text), double.Parse(textBox3.Text)) == null)
            {
                MessageBox.Show("无实根啊！","错误提示",MessageBoxButtons.OK,MessageBoxIcon.Warning); return;
            }
            textBox4.Text = Root2(double.Parse(textBox1.Text), double.Parse(textBox2.Text), double.Parse(textBox3.Text))[0].ToString();
            textBox5.Text = Root2(double.Parse(textBox1.Text), double.Parse(textBox2.Text), double.Parse(textBox3.Text))[1].ToString();
        }
    }
}