using System;
namespace ConcoleApp1
{
    public class QEClass
    {
        public double a;
        public double b;
        public double c;
        public QEClass(double _a, double _b, double _c)
        {
            a = _a;
            b = _b;
            c = _c;
        }

        public string Resolve(int sign)
        {
            string iota = "";
            string result = (-b / (2.0 * a)).ToString("F2");
            double d = b * b + sign * 4 * a * c;
            if (d < 0) { iota = "i"; d = -d; }
            d = System.Math.Sqrt(d) / (2 * a);

            return String.Concat(result,
                        (sign > 0) ? "+" : "-", d.ToString("F2"), iota);
        }

    }

    class Program
    {
        static void Main(string[] args)
        {
            QEClass calculator = new QEClass(5, 3, 2);
            string s = String.Concat(calculator.Resolve(+1),
            " ",
            calculator.Resolve(-1));
            Console.WriteLine(s);
            Console.ReadKey();
        }

    }

}