Write a method for solving a quadratic equation using the following header: publ

Question

Write a method for solving a quadratic equation using the following header:

public static int solveQuadratic(double[] eqn, double[] roots)

The coefficients of a quadratic equation ax2 + bx + c = 0 are passed to the array eqn and the real roots are stored in roots. The method returns the number of real roots. See Programming Exercise 3.1 on how to solve a quadratic equation.

Write a program that prompts the user to enter values for a, b, and c and displays the number of real roots and all real roots.

Here codes, I tried to run it into live lab but I got it wrong. I don't see whats wrong with it.

import java.util.Scanner;

   public class quadraticequation{
   public static void main(String[] args) {
   Scanner input = new Scanner(System.in);

   // Use "print" so that the input can follow the prompt
   System.out.print("Enter a value for a: ");
   double a = input.nextDouble();

   System.out.print("Enter a value for b: ");
   double b = input.nextDouble();

   System.out.print("Enter a value for c: ");
   double c = input.nextDouble();

   input.close();

   // solveQuadratic function call following this assignment.
   double [] roots = new double[2];

   solveQuadratic(new double[] { a, b, c }, roots ) ;

   System.out.printf("Roots: [%.2f, %.2f] ", roots[0], roots[1]);
   System.out.printf("Sum of roots: %.2f ", roots[0] + roots[1]);
   }

   public static int solveQuadratic(double[] eqn, double[] roots) {
   // Set the variables a, b, and c to values in the array
   double a = eqn[0],
b = eqn[1],
c = eqn[2];

   double discriminant = Math.pow(b, 2) - 4 * a * c;

   roots[0] = (-b + Math.sqrt(discriminant )) / (2 * a);
   roots[1] = (-b - Math.sqrt(discriminant )) / (2 * a);

   return 0;
   }
   }

Explanation / Answer

import java.util.Scanner;
   public class quadraticequation{
public static void main(String[] args) {
   Scanner input = new Scanner(System.in);
   // Use "print" so that the input can follow the prompt
   System.out.print("Enter a value for a: ");
   double a = input.nextDouble();
   System.out.print("Enter a value for b: ");
   double b = input.nextDouble();
   System.out.print("Enter a value for c: ");
   double c = input.nextDouble();
   input.close();
   // solveQuadratic function call following this assignment.
   double [] roots = new double[2];
   if(solveQuadratic(new double[] { a, b, c }, roots ) >=1)
   {
   System.out.printf(" Roots: [%.2f, %.2f] ", roots[0], roots[1]);
   System.out.printf(" Sum of roots: %.2f ", roots[0] + roots[1]);
   }
   else
   System.out.println(" No real roots available");
   }
   public static int solveQuadratic(double[] eqn, double[] roots) {
   // Set the variables a, b, and c to values in the array
   double a = eqn[0],b = eqn[1],c = eqn[2];
   //double discriminant = Math.pow(b, 2) - 4 * a * c;
   if((b*b -4*a*c)>0)
   {
   roots[0] = (-b + Math.sqrt(b*b -4*a*c)) / (2 * a);
   roots[1] = (-b - Math.sqrt(b*b -4*a*c)) / (2 * a);
   return 2;
   }
   else if(b*b == 4*a*c)
   {
   roots[0] = (-b ) / (2 * a);
   roots[1] = -b/(2*a);
   return 1;
   }

   return 0;
   }
   }

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