public static void Main()
Console.WriteLine("Giai phuong trinh bac hai\n");
Console.Write("Nhap gia tri cua a: ");
a = Convert.ToInt32(Console.ReadLine());
Console.Write("\nNhap gia tri cua b: ");
b = Convert.ToInt32(Console.ReadLine());
Console.Write("\nNhap gia tri cua c: ");
c = Convert.ToInt32(Console.ReadLine());
Console.Write("Phuong trinh co mot nghiem duy nhat.\n");
Console.Write("Nghiem duy nhat cua phuong trinh la = {0}\n", x1);
Console.Write("Phuong trinh co hai nghiem thuc phan biet\n");
x1 = (-b + Math.Sqrt(x)) / (2 * a);
x2 = (-b - Math.Sqrt(x)) / (2 * a);
Console.Write("Nghiem thu nhat: x1 = {0}", x1);
Console.Write("Nghiem thu nhat: x2 = {0}", x2);
Console.Write("Phuong trinh vo nghiem");