Operations Class

package com.ruminay.math;
import java.util.Scanner;
import java.lang.Math;

public class Operations {


    public void quadratic(){

        Scanner scanObj = new Scanner(System.in);
        double a = 0; //ax^2
        double b = 0; //bx
        double c = 0; //c
        double dis = 0; //The discriminant (b^2-4ac)
        double x1 = 0; //first, sometimes only, root
        double x2 = 0; //second root. Only used when there are two roots.

        System.out.println("------------------------------------------------"); //Signify new section.
        System.out.println("aX^2+bX+c=0");
        System.out.println("Please input a, b, and c. Doubles are allowed.");
        System.out.print("a?:"); a=scanObj.nextDouble();
        System.out.print("b?:"); b=scanObj.nextDouble();
        System.out.print("c?:"); c=scanObj.nextDouble();
        System.out.println();

        dis=((b*b)-(4*a*c));
        if(dis==0) //first case
        {
            x1=(-b)/(2*a);
            System.out.println("\tDiscriminant = 0. One real root.");
            System.out.println("\tX = "+x1);
        }
        if(dis>0) //second case
        {
            x1=((-b)+(Math.sqrt((b*b)-(4*a*c))))/(2*a);
            x2=((-b)-(Math.sqrt((b*b)-(4*a*c))))/(2*a);
            System.out.println("\tDiscriminant > 0. Two real roots.");
            System.out.println("\tX1 = "+x1);
            System.out.println("\tX2 = "+x2);
        }
        if(dis<0) //third case
        {
            System.out.println("\tDiscriminant < 0. No real roots.");
        }


    }
    public void linear(){

        Scanner scanObj = new Scanner(System.in);
        double x = 0;
        double y = 0;

        double a,b,c,d,e,f = 0;

        System.out.println("------------------------------------------------"); //Signify new section.
        System.out.println("aX+bY=c"); //Tell the user the equations being used.
        System.out.println("dX+eY=f");
        System.out.println("Please input a, b, c, d, e, and f. Doubles are allowed.");
        System.out.print("a?:"); a=scanObj.nextDouble(); //Get all the variables. No \n's are necessary because the scanner makes one when taking input.
        System.out.print("b?:"); b=scanObj.nextDouble();
        System.out.print("c?:"); c=scanObj.nextDouble();
        System.out.print("d?:"); d=scanObj.nextDouble();
        System.out.print("e?:"); e=scanObj.nextDouble();
        System.out.print("f?:"); f=scanObj.nextDouble();

        x=((e*c-b*f)/(e*a-b*d));
        y=((c-a*x)/b);

        System.out.println("\tX = "+x);
        System.out.println("\tY = "+y);

    }
}