1) \(\left(x+8\right)⋮x\)
\(\Rightarrow x+8-x⋮x\)
\(\Rightarrow8⋮x\)
\(\Rightarrow x\in U\left(8\right)=\left\{-1;1;-2;2;-4;4;-8;8\right\}\left(x\in Z\right)\)
2) \(3x+16⋮x+4\)
\(\Rightarrow3x+16-3\left(x+4\right)⋮x+4\)
\(\Rightarrow3x+16-3x-12⋮x+4\)
\(\Rightarrow4⋮x+4\)
\(\Rightarrow x+4\in U\left(4\right)=\left\{-1;1;-2;2;-4;4\right\}\)
\(\Rightarrow x\in=\left\{-5;-3;-6;-2;-8;0\right\}\left(x\in Z\right)\)