[tex]A = \{1,2\}\times \{3,4,5\} \\ \\ $Notam cu $ | M| $ cardinalul unei multimi $ M.$\\ \\ Stim ca: $ |M\times N| = |M|\cdot |N| \\ \\ \Rightarrow |A| = \Big|\{1,2\} \times \{3,4,5\}\Big| = \Big|\{1,2\}\Big|\cdot \Big|\{3,4,5\}\Big| = 2\cdot 3 = 6 \\ \\ \Rightarrow $ Multimea A are 6 elemente. $ \\ \\ \Rightarrow $ Numarul submultimilor multimii A este: $ \\ \\ C_6^{0}+C_6^1+C_6^2+...+C_6^6 = 2^6 =64[/tex]
