Kvadratna jednacina

#include <iostream>
#include <cmath>
    using namespace std;
    main()
{
    float a, b, c, D, xim, x1, x2, x3, x4, m, s1, s2, t;
    cin  >>  a  >>  b  >>  c;
    D = b*b - 4*a*c;
    if (D<0)
        {
        xim = sqrt(abs(D));
        t = ((-1)*b)/(2*a);
        m = xim/(2*a);
        cout  <<  "t1 = "  <<  t  <<  " + j"  <<  m << endl;
        cout  <<  "t2 = "  <<  t  <<  " - j"  <<  m  << endl;
        }
        else if  (D>=0)
            {
            s1 = ((-1)*b)/(2*a);
            s2 = (sqrt(abs(D)))/(2*a);
            if (s1 + s2 < 0)
                {
                x1 = sqrt (abs(s1+s2));
                cout << "x1 =  j" << x1 << endl;
                cout << "x2 = -j" << x1 << endl;
                }
                    else
                        {
                        x1 = sqrt (s1+s2);
                        x2 = (-1) * x1;
                        cout << "x1 = " << x1 << endl;
                        cout << "x2 = " << x2 << endl;
                        }
            if (s1 - s2 < 0)
                {
                x3 = sqrt (abs(s1-s2));
                cout << "x3 =  j" << x3 << endl;
                cout << "x4 = -j" << x3 << endl;
                }
                    else
                        {
                        x3 = sqrt (s1-s2);
                        x4 = (-1) * x3;
                        cout << "x3 = " << x3 << endl;
                        cout << "x4 = " << x4 << endl;
                        }
                }
    system ("PAUSE");
}