using System;

​

public class Program

{

    public static void Main()

    {

        double a = 1;

        double b = -5;

        double c = 4;

        double D = (b * b) - (4 * a * c);

        double КореньD = Math.Sqrt(D);

        double x1 = (-b + КореньD) / (2 * a);

        double x2 = (-b - КореньD) / (2 * a);

        Console.WriteLine("D = " + D);

        Console.WriteLine("Корень из D = " + КореньD);

        Console.WriteLine("");

        Console.WriteLine("x1 = " + x1);

        Console.WriteLine("x2 = " + x1);

    }

}