Đáp án:
1)
$6\vdots x+2$
$\Rightarrow x+2\in Ư(6)=\pm1,\pm2,\pm3,\pm6$
$\Rightarrow x \in \{-3,-1,-4,0,-5,1,-8,4\}$
Do $x\in N$ nên $x\in \{0,1,4\}$
2)
$6\vdots x-1$
$\Rightarrow x-1\in Ư(6)=\pm1,\pm2,\pm3,\pm6$
$\Rightarrow x \in \{0,2,-1,3,-2,4,-5,7\}$
Do $x\in N$ nên $x\in \{0,2,3,4,7\}$
3)
$6\vdots x-2$
$\Rightarrow x-2\in Ư(6)=\pm1,\pm2,\pm3,\pm6$
$\Rightarrow x \in \{1,3,0,4,-1,5,-4,8\}$
Do $x\in N$ nên $x\in \{0,1,3,4,5,8\}$
4)
$7\vdots x+2$
$\Rightarrow x+2\in Ư(7)=\pm1,\pm7$
$\Rightarrow x \in \{-3,-1,-9,5\}$
Do $x\in N$ nên $x=5$
5)
$7\vdots 2-x$
$\Rightarrow 2-x\in Ư(7)=\pm1,\pm7$
$\Rightarrow x \in \{3,1,9,-5\}$
Do $x\in N$ nên $x\in\{1,3,9\}$
