double a,b,c,il,dis,d,x1,x2;
        a=Double.parseDouble(t1.getText());
        b=Double.parseDouble(t2.getText());
        c=Double.parseDouble(t3.getText());
        if (a==0)
        {
            if(b==0)
            {
                if(c==0)
                {
                l1.setText("Alles gleich ");
                }else
                {
                 l1.setText("Es gibt keine Lösung");
                }
            }else
            {
                il=-c/-b;
                l1.setText("x= "+il);
            }
        }else
        {
         dis=(b*b)-(4*a*c);
         if(dis>0)
         {
            d= Math.sqrt(dis);
            x1=-(b-d)/(2*a);
            x2=-(b+d)/(2*a);
            l1.setText("x1 = "+x1+" x2 = "+x2);
         }else
         {
            if(dis==0)
            {
                il=-b/(2*a);
             l1.setText("x = "+il);
            }else
            {
             l1.setText("Es gibt keine Lösung!");
            }
         }
        }