How to make a polynomial method and refer to it?

Question

Java

Good afternoon.
There is a method.
Polynomial
3X^2 -8X + 4
I want to make a method that will take the x value and run it through the formula and return the result.
Looks like he did something. But how now to give the user the opportunity to access this function?

import java.util.Scanner;
public class Polinom 
{
    public static void main ( String[] args )  
    {
     System.out.print("Введите число"); 

    }
    public double polinom(double x) 
    {
      Scanner number = new Scanner(System.in);
      x = number.nextDouble();
      double resultat = 3*Math.pow(x, 2)-8*x+4;
      resultat = Math.round(resultat);
      System.out.println(resultat);
      System.out.print("Функция сработала"); 
      return resultat;
      }
}