main()
{
        float k=0, x, u=(x*x)/2, r, s=u, es=1e-3;
        while (fabs(u)>=es)
        {

                r=(pow(-1, k+1)*pow(x,k+2))/(k+1);
                u*=r;
                s+=u;
                k++;
        }
        cout<<"Sum = "<<s;
        getch();
}

main()
{
        int n=0, u=1;
        float eps=1e-3, s=u, s1, x;
        while (abs(u)>=eps)
        {
                n++;
                u=pow(-1,n)*n;
                s+=u;
        }
               s1=1/(1-x);
               if (fabs(s-s1)<=eps) cout<<"To4noe zna4enie";
               else cout<<"Neto4noe zna4enie";
        getch();
}

const double eps = 1e-8;

double series(double x, double epsilon)
{
    double term = x*x/2.0, sum = term;
    for(int k = 0; fabs(term) > epsilon; ++k)
    {
        sum += (term *= -x*(k+1)/double((k+2)*(k+3)));
    }
    return sum;
}

int main(int argc, const char * argv[])
{
    for(double x = -1.0; x <= 1.0; x += 0.1)
    {
        cout << fixed << setprecision(2) << setw(5) << x
             << setprecision(10) << setw(15) << series(x,eps) << endl;
    }
}

const double eps = 1e-8;

double series(double x, double epsilon)
{
    double term = 1.0, sum = term;
    while(fabs(term) > epsilon)
    {
        sum += term *= x;
    }
    return sum;
}

int main(int argc, const char * argv[])
{
    for(double x = -0.9; x <= 0.9; x += 0.1)
    {
        cout << fixed << setprecision(2) << setw(5) << x
            << setprecision(10) << setw(15) << series(x,eps)
            << setw(15) << (1.0/(1-x)) << endl;
    }
}