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Java

Posted by Timothy Van Cauwenberge
Timothy Van Cauwenberge
8,958 Points

Help with creating quadratic function program

Im trying to create a quadratic function program and I believe I have the right formula plugged in but I'm not getting the correct answer. If you can help at all let me know. Thanks. Sorry if the code gets posted unorganized.

public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        double x1 = 0, x2 = 0;
        double a = 0, b = 0, c = 0, d = 0;

              System.out.println("\nThe Quadratic Formula is ax^2 + bx + c = 0. \n Please enter a: ");
       a = input.nextInt();
              System.out.println("Please enter b: ");
       b = input.nextInt();
              System.out.println("Please enter c: ");
       c = input.nextInt();

       d = Math.sqrt(Math.pow(b, 2) - 4 * a * c);

        if(d > 0)
        {
            x1 = (- b - d) / 2 * a;
            x2 = (- b + d) / 2 * a;
            System.out.println("First root is:" + x1);
            System.out.println("Second root is:" + x2);
        }
        else if(d == 0)
        {
            System.out.println("Roots are equal");
            x1 = ( - b - d) / 2 * a;
            System.out.println("Root:" + x1);
        }
        else
        {
            System.out.println("Roots are imaginary or negative");
        }
    }
}
Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

fixed code formatting

1 Answer

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Timothy,

The discriminant is the part inside the square root not including the square root itself. You should only calculate b^2 - 4ac for that part.

You'll need to update the if block to calculate the square root of the variable d since it was removed from the discriminant.

Also, the quadratic formula has 2a for the denominator. You'll need to wrap all your 2 * a with parentheses. Otherwise the a will be treated as if it's in the numerator based on left to right evaluation.

Also, when d is 0 you don't have to worry about subtracting it in the formula.