Phuong trinh bac 2

//@___justkiddin
#include <bits/stdc++.h>

using namespace std;

float a,b,c;
float x1,x2;

int giaiPT(){
    float delta = b*b - 4*a*c;
    if(delta < 0){
        x1 = x2 = 0.0;
        return 0;
    }
    else if(delta == 0){
        x1 = x2 = -b / (2*a);
        return 1;
    }
    else{
        delta = sqrt(delta);
        x1 = (-b + delta) / (2*a);
        x2 = (-b - delta) / (2*a);
        return 2;
    }
}

int main(){
    do{
        cout << "Nhap a (a!=0): ";  cin >> a;
        cout << "Nhap b: "; cin >> b;
        cout << "Nhap c: "; cin >> c;
    }
    while(a == 0);

    int numNo = giaiPT();
    if(numNo ==0 )
        cout<<"Phuong trinh da cho vo nghiem";
    else
        if(numNo==1)
            cout << fixed << setprecision(2) << "Phuong trinh da cho co nghiem kep x = " << x1;
        else{
            cout << "Phuong trinh da cho co hai nghiem phan biet"<<endl;
            cout << "x1 = " << x1 << endl;
            cout << "x2 = " << x2 << endl;
        }
}