equation with a variable on the 2nd power, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("add meg a-t:");
            double a = console.Readline();
            console.Writeline("add meg b-t:");
            double b = Console.ReadLine();
            console.writeline("add meg c-t:");
            double c = console.Readline();
            double gyok = math.pow(b,2)-4*a*c;
            if (gyok<0);
                console.Writeline(" nem megoldható");
            else;
                console.Writeline("x1=",(-b-math.sqrt(gyok))/2*a);
                Console.Writeline("x2=",(-b+math.sqrt(gyok))/2*a);
            console.Readline();
            
        }
    }
}

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Compilation time: 0,12 s