6.A={3,6,9} B={6,12,18..} B nu include toata multimea A, doar partial
7. A={1,2} B={1,2,5,10} AUB={1,2,5,10} Aintersecatc cu B={1,2} si A|B={multime vida}
8.A={1,2,43,4,5} B=1,2,3} AUB ={1,2,3,4,5,} aintersectat cu B={1,2,3} A\B={4,5} B|A={multime vida
