Răspuns :

3x+2 / x+1 ∈ Z <=> 3(x+1)-1 / x+1  ∈ Z <=> [ 3(x+1)/ x+1  - 1/ x+1 ] ∈ Z <=>
<=> 3- 1/x+1  ∈ Z <=> 1/ x+1 ∈ Z ( caci 3∈Z )<=> x + 1 =1 sau x + 1 =-1<=>x = 0 sau x = -2
 A = { -2; 0 }
x+1| 3x+2
x+1| x+1⇒x+1| 3x+3⇒x+1| (3x+2-3x-2)⇒x+1|1⇒x+1∈{-1;1}⇒x∈{-2;0}