Evaluating the Polynomial

import java.io.*;

class evalPoly
{
  public static void main (String[] args ) throws IOException
  {
    BufferedReader userin =  new BufferedReader(new InputStreamReader(System.in) );

    String xChars;                 // character version of x, from the user    
    double x;                      // a value to use with the polynomial
    double result;                 // result of evaluating the polynomial at x
    String response = "y";         // "y" or "n"

    while ( response.equals( "y" ) )    
    {
       // prompt the user and get a value for x
       System.out.println("Enter a value for x:") ;
       xChars = userin.readLine() ;
       x   = ( Double.valueOf( xChars ) ).doubleValue();

       // evaluate the polynomial
       result = ______________________________ ;   

       // print out the result

       ________________________________________ ;

       // ask the user if program should continue
       System.out.println("continue (y or n)?");

       response = userin.readLine();      
    }

  }
}