\(\left(3a+11\right)⋮\left(a+2\right)\\ \Rightarrow\left[3\left(a+2\right)+5\right]⋮\left(a+2\right)\\ \Rightarrow5⋮\left(a+2\right)\left[vì:3\left(a+2\right)⋮\left(a+2\right)\right]\\ \Rightarrow\left(a+2\right)\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\\ \left(a+2\right)\in\left\{-1;-3;3;-7\right\}\)