Calculer résistance équivalent pour parallèle

import java.util.Scanner;
public class CalculResis 
{
 public static void main(String[] args) 
 {
   Scanner sc=new Scanner(System.in);
    System.out.println("Entrer la valeur de r1:");
    double r1=sc.nextDouble();
    System.out.println("Entrer la valeur de r2:");
    double r2=sc.nextDouble();
    System.out.println("Entrer la valeur de r3:");
    double r3=sc.nextDouble();
   
    double Rser= result(r1,r2,r3);
    double Rpar= result1(r1,r2,r3);
    double Rpar1=result2(r1,r2,r3);
    System.out.println(""+Rser);
    System.out.println(""+Rpar);
    System.out.println(""+Rpar1);
 }

 private static double result1(double r1, double r2, double r3) 
 {
  //double Rpar=((r1*r2*r3) / (r1*r2)+(r1*r3)+(r2*r3)); 
  double Rpar=( (1/ ( (1/r1)+(1/r2)+(1/r3) ) ) );
  return Rpar;
 }

 private static double result2(double r1, double r2, double r3) 
 {
  double Rpar1=(r1*r2*r3/(r1+r2+r3));
  return Rpar1;
 }
 private static double result(double r1, double r2, double r3) 
 {
  double Rser=r1+r2+r3;
  return Rser;
 }
}