9/2x+3 € Z
2x+3 | 9
2x+3 | D9
=> 2x+3 | {-1;1;-3;3;-9;9}
2x+3 = -1 => 2x = -4 => x = -2 €Z
2x+3 = 1 => 2x =-2 => x = -1 €Z
2x+3 = -3 => 2x = -6 => x = -3 €Z
2x+3 = 3 => 2x = 0 => x = 0 €Z
2x+3 = -9 => 2x = -12 => x = -6 €Z
2x+3 = 9 => 2x = 6 => x = 3 €Z
x€{-6;-3;-2;-1;0;3}