Вычислить сумму бесконечного ряда, используя подпрограммы

#include <iostream>
#include <cstdlib>
#include <clocale>
#include <cmath>
 
unsigned Factorial(unsigned const i)
{
    return i ? i * Factorial(i - 1) : 1;
}
 
double CommonMember(unsigned const i, double const x)
{
    return pow(-1, i) * sqrt(pow(x, i) + pow(x, i - 1) + 1) / Factorial(i);
}
 
int main()
{
    setlocale(LC_ALL, "rus");
    double const x = 0.81, precision = 4e-5;
    double sum = 0, commonmember = 0;
    unsigned i = 0;
    for(i = 0; fabs(commonmember = CommonMember(i, x)) > precision; ++i)
    {
        sum += commonmember;
        std::cout << "i: " << i << "\n";
        std::cout << "commonmember: " << commonmember << "\n";
        std::cout << "sum: " << sum << "\n\n";
    }
    std::cout << "Result:\ni: " << i << "\n";
    std::cout << "commonmember: " << commonmember << "\n";
    std::cout << "sum: " << sum << "\n\n";
    system("pause");
    return 0;
}