Răspuns:
[tex] x \in \Big\{ 1, \: 2, \: 3, \: 6, \: 8, \: 9, \: 18 \Big\} [/tex]
Explicație pas cu pas:
[tex] x \in \Bbb{N}^{*} [/tex]
[tex] \dfrac{18}{x} \in \Bbb{N}\Longleftrightarrow \underline{x \in \mathcal{D}_{18}} [/tex]
[tex] \mathcal{D}_{18} = \Big\{1, \: 2, \: 3, \: 6, \; 8, \: 9, \: 18 \Big\} [/tex]
[tex] \Longrightarrow \boldsymbol {x \in \Big\{1, \: 2, \: 3, \: 6, \; 8, \: 9, \: 18 \Big\}} [/tex]
