Example: Java Program to Find the Roots of a Quadratic Equation using sqrt() Function

// Java Program to Find the Roots of a Quadratic Equation using sqrt() Function
import java.util.Scanner;

public class Main {

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

        double p, q, r, d, r1, r2, rp, ip;

        // p, q and r - To store the real numbers
        // d  - To store the discriminant
        // r1 - To store the first root
        // r2 - To store the second root
        // rp - To store the real part
        // ip - To store the image part

        System.out.println ("-----Enter the these coefficients a, b and c----");
        p = in.nextFloat();
        q = in.nextFloat();
        r = in.nextFloat();

        d = q * q - 4 * p * r;
        
        if (d > 0) {
            // It is the condition for real and different roots

            r1 = (-q + Math.sqrt(d)) / (2 * p);
            r2 = (-q - Math.sqrt(d)) / (2 * p);
            System.out.println ("\nThe r1 = " + r1 + " & r2 = " + r2);
        } else if (d == 0) {
            // It is the condition for real and equal roots

            r1 = r2 = -q / (2 * p);
            System.out.println ("\nThe r1 = r2 = " + r1 + ";");
        } else {
            // if the roots are not real number

            rp = -q / (2 * p);
            ip = Math.sqrt(-d) / (2 * p);
            System.out.printf ("\nThe r1 = %.2f+%.2fi & r2 = %.2f-%.2fi\n", rp, ip, rp, ip);
        }
    }
}