ION PÄTRAĆCU 1, CÄTÄLIN I. BARBU 2 1. âFraĆŁii BuzeĆtiâ National College, Department of Mathematics, Ion Cantacuzino 15, 200818 Craiova, Romania, e-mail: patrascu_ion@yahoo.com
2. âVasile Alecsandriâ National College, Department of Mathematics, Vasile Alecsandri 37, 600011 BacÄu, Romania, e-mail: kafka_mate@yahoo.com