Question

Write a Java program that solves a set of quadratic equations as per Requirement #1 (without using global variables), and reads an integer number entered in the command line, as follows: > java program_name input_number and depending on the value of this number does the following:

1) If the number entered is positive, the program shall solve (running in a loop) as many quadratic equations of the following form, as the input_number tells:

a * x2 + b * x + c = 0

where coefficients a, b and c are double values, entered from the keyboard as per Requirement #3.

2) If the input number entered in the command line is not positive, the program shall print the following message to the screen and exit:

A positive value shall be entered in the command line.

3) The values of coefficients a, b and c, as listed in Requirement #1, shall be read from the keyboard by the program with the following message on the screen, each time a new coefficient is needed:

Please enter the next coefficient of a quadratic equation:

4) If the coefficient a is a zero, the program shall display the following message on the screen (first line) repeating the request for another value of a (second line):

Coefficient a cannot be a zero. Enter the correct value. Please enter the next coefficient of a quadratic equation:

5) When the program solves the quadratic equation (calculates the roots), as per Requirement #1, the following output shall be displayed on the screen:

<one empty line>

Quadratic equation with the following coefficients

a: <value>; b: <value>; c: has

the following roots: <root1>and <root2>

6) In case the quadratic equation for given coefficients does not have roots, the program shall print the following message, and continue operation for the next set of coefficients:

<one empty line>

Quadratic equation with the following coefficients:

a: <value>; b: <value>; c: <value> does not have roots

Answer 1

Code is Given Below:

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import java.util.Scanner;

public class Quadratic {
   public static void main(String[] args) {
       //creating scanner object to get input from user
       Scanner scn=new Scanner(System.in);
       //asking user to input
       System.out.println("Quadratic Equation solver");
       System.out.print("Enter Positive number: ");
       int n=scn.nextInt();
       //cheking if n is negative
       if(n<=0) {
           System.out.println("A positive value shall be entered in the command line.");
           return;
       }
       int i=1;
       //loop will run n times
       while(n>=i) {
           //asking user for input
           System.out.print("Please enter the next coefficient of a quadratic equation: ");
           double a=scn.nextDouble();
           if(a==0) {
               System.out.println("Coefficient a cannot be a zero. Enter the correct value. ");
               continue;
           }
           System.out.print("Please enter the next coefficient of a quadratic equation: ");
           double b=scn.nextDouble();
           System.out.print("Please enter the next coefficient of a quadratic equation: ");
           double c=scn.nextDouble();
           //finding discreminant
           double d=b*b - 4*a*c;
           //checking if equation has root or not
           if(d<0) {
               System.out.println("a: <"+a+">; b: <"+b+">; c: <"+c+"> does not have roots");
               i++;
               System.out.println();
               continue;
           }
           //finding roots
           double root1 = (-b + Math.sqrt(d))/2*a;
           double root2 = (-b - Math.sqrt(d))/2*a;
           //displaying result
           System.out.println("a: <"+a+">; b: <"+b+">; c: <"+c+"> has the following root");
           System.out.println("<"+root1+"> and <"+root2+">");
           i++;
          
           System.out.println();
       }
   }

}

Output:

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Code Snapshot:

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