7/x-2 x-2 apartine divizorilor lui 7 {1,7} x-2=1            x-2=7 x=1+2           x=7+2 x=3              x=9 x apartine {3;9}

[latex]B={xin N| frac{7}{x-2}in N } \ frac{7}{x-2} in N \ x-2|7 \ x-2 in{1,7}|+2 \ x in {3,9}[/latex]