PTBac2.java

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package btvn1;

import java.util.Scanner;

/**
 *
 * @author Kawaii
 */
public class PTBac2 {

    public static void main(String[] args) {
        float a, b, c;
        Scanner sc = new Scanner(System.in);
        System.out.print("Nhap a: ");
        a = sc.nextInt();
        System.out.print("Nhap b: ");
        b = sc.nextInt();
        System.out.print("Nhap c: ");
        c = sc.nextInt();
        if (a == 0) {
            if (b == 0 && c == 0) {
                System.out.println("PT co vo so nghiem");
            } else if (b == 0 && c != 0) {
                System.out.println("PT vo nghiem");
            } else {
                System.out.println("PT co 1 nghiem duy nhat: x = " + -c / b);
            }
        } else {
            float delta = b * b - 4 * a * c;
            if (delta == 0) {
                System.out.println("PT co nghiem kep x1 = x2 = " + -b / 2 * a);
            } else if (delta < 0) {
                System.out.println("PT vo nghiem");
            } else {
                System.out.println("PT co 2 nghiem x1 = " + (b + Math.sqrt(delta)) / (2 * a) + " va x2 = " + (-b + Math.sqrt(delta)) / (2 * a));
            }
        }
    }
}