Question

Daca A e reunita cu B={2,5,6,9,12} , Ae intersectata cu B={5,6,12} , A-B={2} atunci mulțimea B are ..... elemente​

Answer 1

Răspuns:

{5;6;12}⊂A si B ;  A={2;5;6;12}   B={5;6;12;9}

Explicație pas cu pas:

Answer 2

$\it A-B=\{2\} \Rightarrow 2\in A\ \ \c{s}i\ 2\notin B\ \ \ \ (1)\\ \\ A\cap B=\{5,\ 6,\ 12\} \Rightarrow \{5,\ 6,\ 12\} \subset A\ \c{s}i\ \{5,\ 6,\ 12\} \subset B\ \ \ \ (2)\\ \\ A\cap B=\{2,\ 5,\ 6,\ 9,\ 12\} \Rightarrow A\subset \{2,\ 5,\ 6,\ 9,\ 12\} \ \c{s}i\ B\subset \{2,\ 5,\ 6,\ 9,\ 12\} \ \ (3)\\ \\ (1),\ (2),\ (3) \Rightarrow \it A=\{2,\ 5,\ 6,\ 12\};\ \ B=\{5,\ 6,\ 9,\ 12\}$