public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        double Delta(double a, double b, double c)
        {
            return b * b - 4 * a * c;
        }
       public void Pierwiastki(double a, double b, double c, out double x1, out double x2)
        {
            if (Delta(a, b, c) == 0)
            {
                x1 = (-b) / (2 * a);
                x2 = 0;
            }
            else
            {
                x1 = ((-b) - (Math.Sqrt(Delta(a, b, c)))) / (2 * a);
                x2= ((-b) + (Math.Sqrt(Delta(a, b, c)))) / (2 * a);
            }



        }
           private void btn1_Click(object sender, RoutedEventArgs e)
        {
            double a = Convert.ToDouble(txtA.Text);
            double b = Convert.ToDouble(txtB.Text);
            double c = Convert.ToDouble(txtC.Text);
            double x1, x2;
            Pierwiastki(a, b, c,out x1,out x2);
            lblWynik.Content = x1.ToString("F2");
            lblWynik.Content = x2.ToString("F2");

        }


    }
}