QuadraticEquationRoots

using System;
class QuadraticEquationRoots
{
  static void Main()
  {
    //Write a program that enters the coefficients a, b and c of a quadratic equation
    //a*x2 + b*x + c = 0
    //and calculates and prints its real roots. Note that quadratic equations may have 0, 1 or 2 real roots.

    Console.Write("Please enter the coefficient number a:");
    double a = double.Parse(Console.ReadLine()); // quadratic coeficient a.
    Console.Write("Please enter the coefficient number b:");
    double b = double.Parse(Console.ReadLine()); // linear coeficient b
    Console.Write("Please enter the constant term c:");
    double c = double.Parse(Console.ReadLine()); // free term
    double delta = b * b - 4 * a * c;
    double x1, x2;

    if (a == 0 && b == 0 && c == 0)
    {
      Console.WriteLine("The possible roots are infinite!");
    }
    else if (a == 0 && b == 0 && c != 0)
    {
      Console.WriteLine("There are no real roots!");
    }
    else if (a == 0 && b != 0)
    {
      Console.WriteLine("Your equation is linear and has root x = {0}", -(c / b));
    }
    else if (delta < 0)
    {
      Console.WriteLine("The quadratic equation has no real roots.");
    }
    else
    {
      x1 = ((-b + Math.Sqrt(delta))) / (2 * a);
      x2 = ((-b - Math.Sqrt(delta))) / (2 * a);
      Console.WriteLine("The equation has roots x1={0} and x2={1}", x1, x2);
    }
  }
}