BaiTapGiaiPhuongTrinhBacHai.java

import java.util.Scanner;

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

      System.out.print("nhap so a: ");
      double a = scanner.nextDouble();

      System.out.print("nhap so b: ");
      double b = scanner.nextDouble();

      System.out.print("nhap so  c: ");
      double c = scanner.nextDouble();

      if (a == 0) {
         // Giải phương trình bậc nhất
         if (b == 0) {
            if (c == 0) {
               System.out.println("phuong trinh vo so nghiem");
            } else {
               System.out.println("phuong trinh vo nghiem.");
            }
         } else {
            double x = -c / b;
            System.out.println("Nghiem cua phuong trinh la  x = " + x);
         }
      } else {
         double delta = b * b - 4 * a * c;

         if (delta < 0) {
            System.out.println("Phuong trinh vo nghiem.");
         } else if (delta == 0) {
            double x = -b / (2 * a);
            System.out.println("Phuong trinh co nghiem kep x = " + x);
         } else {
            double x1 = (-b + Math.sqrt(delta)) / (2 * a);
            double x2 = (-b - Math.sqrt(delta)) / (2 * a);
            System.out.println("Phuong trinh co hai nghiem phan biet:");
            System.out.println("x1 = " + x1);
            System.out.println("x2 = " + x2); 
         }
      }

      scanner.close();
   }
}