We classify all cubic di erential systems with exactly six ane real invariant straight lines (taking into account their parallel multiplicity) of four slopes. One invariant strait line of the rst slope has parallel multiplicity m; m = 1; 2; 3: We proove that there are ve distinct classes of such systems. For every class we carried out the qualitative investigation on the Poincare disk.

Sunt clasi cate sistemele diferentiale cubice cu exact sase drepte a ne reale invariante (tin^anduse cont de multiplicitatea paralela) de patru pante. O dreapta de prima panta are multiplicitatea paralela m; m = 1; 2; 3: Se arata ca exista cinci clase distincte de astfel de sisteme. Fiecare clasa este studiata din punct de vedere calitativ si pe discul Poincare sunt construite portretele de faza.