Question

Exercițiul 3. Aflați produsul elementelor mulțimii ​

Answer 1

$\it \dfrac{-2}{x-1}\in\mathbb{N} \Rightarrow x-1 < 0\ \ \ \ \ (*)\\ \\ \\ x\in\mathnn{Z},\ \ \dfrac{-2}{x-1}\in\mathbb{N} \Rightarrow x-1\in D_{-2}\ \stackrel{(*)}{\Longrightarrow }x-1\in\{-2,\ -1\}\Big|_{+1} \Rightarrow x\in\{-1,\ 0\}\\ \\ \\ M=\{-1,\ \ 0\};\ \ \ -1\cdot0=0$