Lista de exercícios do ensino médio para impressão
(MACKENZIE - 1969) Knowing the set $\,\mathbb{A}\,=\,\lbrace\,\lbrace\,1\,\rbrace , \,\lbrace\,2\,\rbrace,\,\lbrace\,1,\,2\,\rbrace\,\rbrace\,\;$, which one of the following statements is correct?
a)
$\,\{1\}\,\notin \mathbb{A}\,$
b)
$\,\{1\}\,\subset \mathbb{A}\,$
c)
$\,\{1\}\,\cap\,\{2\}\,\not\subset \, \mathbb{A}\,$
d)
$\,2\,\in \mathbb{A}\,$
e)
$\,\{1\}\,\cup\,\{2\}\,\in \, \mathbb{A}\,$