using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Quadratic Expressions Menu");                    

        Console.WriteLine("1. (x-1)(x+2)");                 

        Console.WriteLine("2. -x^2+3x-1");                  

        Console.WriteLine("3. 5x(x+3)-12x");                    

        Console.WriteLine("4. x^3-x(x^2+x-3)");                 

        Console.WriteLine("Select [1-4] only");                 

        int selected  = int.Parse(Console.ReadLine());                  

​

        if (selected ==1){

            Console.WriteLine("Input the value of x");                  

            int x = int.Parse(Console.ReadLine());

            double result = (x-1)*(x+2);

            Console.WriteLine("Result: {0}", result);

        }else if(selected ==2){

            Console.WriteLine("Input the value of x");                  

            int x = int.Parse(Console.ReadLine());

            double result = (Math.Pow(x,2)*-1)+(3*x)-1;

            Console.WriteLine("Result: {0}", result);

        }else if(selected ==3){

            Console.WriteLine("Input the value of x");                  

            int x = int.Parse(Console.ReadLine());

            double result = (5*x)*(x+3)-(12*x);

            Console.WriteLine("Result: {0}", result);

        }else if(selected ==4){

            Console.WriteLine("Input the value of x");                  

            int x = int.Parse(Console.ReadLine());

            double result = (Math.Pow(x,3))-(x*((Math.Pow(x,2))+x-3));

            Console.WriteLine("Result: {0}", result);

        }   

        else{               

            Console.WriteLine("Invalid selection");             

        }

    }

}