Quadratic Equation

using System;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please enter a number for a: ");
            double a = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a number for b: ");
            double b = double.Parse(Console.ReadLine());
            Console.WriteLine("Please enter a number for c: ");
            double c = double.Parse(Console.ReadLine());
            double d = (b * b) - (4 * a * c);

            Console.WriteLine("x1: {0}", -(b + Math.Sqrt(d)) / (2 * a));
            Console.WriteLine("x2: {0}", -(b - Math.Sqrt(d)) / (2 * a));

        }
    }
}