Răspuns:
Explicație pas cu pas:
[tex]\dfrac{15}{3x+1} \in Z\Rightarrow 3x+1\in D_{15}\\~~~~~~~~~~~~~~~~~~~~3x+1\in\{-15,-5,-3,-1,1,3,5,15\}\\~~~~~~~~~~~~~~~~~~~~3x\in\{-16,-6,-4,-2,0,2,4,14\}\\~~~~~~~~~~~~~~~~~~~~x\in\left\{-\dfrac{16}{3},-2,-\dfrac{4}{3}.-\dfrac{2}{3},0,\dfrac{2}{3},\dfrac{4}{3},\dfrac{14}{3}\right\}\\~~~~~~~~~~~~~~~~~~~~x\in\mathbb{Z}\Rightarrow x\in\{-2,0\}[/tex]
