#include <stdio.h>
struct bien {
    float a, b, c;
};
void nhap_bien(float a, float b, float c){
    printf("Nhap he so bac 2, a = ");
    scanf("%f", &a);
    printf("Nhap he so bac 1, b = ");
    scanf("%f", &b);
    printf("Nhap so hang tu do, c = ");
    scanf("%f", &c);
}
void giaiPTBac2(float a, float b, float c) {
    // kiem tra cac he so
    if (a == 0) {
        if (b == 0) {
            printf("Phuong trinh vo nghiem!");
        } else {
            printf("Phuong trinh co mot nghiem: x = %f", (-c / b));
        }
        return;
    }
    // tinh delta
    float delta = b*b - 4*a*c;
    float x1;
    float x2;
    // tinh nghiem
    if (delta > 0) {
        x1 = (float) ((-b + sqrt(delta)) / (2*a));
        x2 = (float) ((-b - sqrt(delta)) / (2*a));
        printf("Phuong trinh co 2 nghiem la: x1 = %f va x2 = %f", x1, x2);
    } else if (delta == 0) {
        x1 = (-b / (2 * a));
        printf("Phong trinh co nghiem kep: x1 = x2 = %f", x1);
    } else {
        printf("Phuong trinh vo nghiem!");
    }
}

/**
 * ham main
 */
int main() {
    struct bien bn;
    nhap_bien(bn.a, bn.b, bn.c);
    giaiPTBac2(bn.a, bn.b, bn.c);
    return 1;
}