Wielomianowy Sekret

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;


double sekret_punktow( int x1, int y1, int x2, int y2, int x3, int y3 )
{
    double wspolczynnik_b = ((y1-y3) * (x1*x1 - x2*x2) - (x1*x1 - x3*x3)*(y1-y2)) / ((x1-x3)*(x1*x1 - x2*x2) - (x1-x2)*(x1*x1-x3*x3));
    double wspolczynnik_a = (y1 - y2 - wspolczynnik_b*(x1 - x2)) / (x1*x1 - x2*x2);

    double wspolczynnik_c = (wspolczynnik_a *x1*x1 + wspolczynnik_b * x1 - y1) * -1;

    return wspolczynnik_c;
}

int main()
{
    srand(time(NULL));

    int sekret = 0;
    cout << "podaj sekretna liczbe: " << endl;
    cin >> sekret;

    int a = (rand() % 5) + 1;
    int b = (rand() % 5) + 1;

    cout << "wybrany wielomian: " << a << "x^2" << " + " << b << "x" << " + " << sekret << endl << endl;

    int lx = rand() % 15 + 3;
    float x1 = lx;
    float y1 = a * lx * lx + b * lx + sekret;
    cout << "x1: " << x1 << "    y1: " << y1 << endl;

    lx = rand() % 10 + 15;
    float x2 = lx;
    float y2 = a * lx * lx + b * lx + sekret;
    cout << "x2: " << x2 << "    y2: " << y2 << endl;

    lx = rand() % 15 + 7;
    float x3 = lx;
    float y3 = a * lx * lx + b * lx + sekret;
    cout << "x3: " << x3 << "    y3: " << y3 << endl;


    cout << "czy chcesz odszyfrowac sekret na podstawie punktow? (y/n)" << endl;
    string input;
    cin >> input;

    if(input == "y")
    {
        double sekretna_liczba = sekret_punktow( x1, y1, x2, y2, x3, y3 );
        cout << "sekret to: " << sekretna_liczba << endl;
    }

    system("pause");
    return 0;
}