#include<conio.h>
#include<stdio.h>
#include<math.h>
void main()
{
    float a,b,c,d;
    printf(" Nhap a,b,c:");
    scanf("%f%f%f",&a,&b,&c);
    if(a==0)//bx+c=0
        if(b==0)//c=0
            if(c==0)
             printf("\n VSN!");
            else
             printf("\n VN!");
         else
        printf("\n PT co nghiem duy nhat:x=%6.2f\n",-c/b);
    else//a!=0
        {
        d=b*b-4*a*c;
        if(d==0)
         printf("\n Nghiem kep:x1=x2=%6.2f",-b/(2*a));
        else//d!=0
            if(d>0)
                printf("\n Co hai nghiem la x1=%6.2f va x2=%6.2f",(-b+sqrt(d))/(4*a),
                  (-b-sqrt(d))/(4*a));
            else//d<0
                printf("\n PTVN!");
        }
        getch();
}