Đề bài không cho điều kiện?
e) \(\left(12-n\right)⋮\left(8-n\right)\)
\(\Rightarrow\left(4+8-n\right)⋮\left(8-n\right)\)
\(\Rightarrow4⋮\left(8-n\right)\)
\(\Rightarrow\left(8-n\right)\inƯ\left(4\right)=\left\{1;-1;2;-2;4;-4\right\}\)
\(\Rightarrow n\in\left\{7;9;6;10;4;12\right\}\)
f) \(\left(27-5n\right)⋮\left(n+3\right)\)
\(\Rightarrow\left[\left(27-5n\right)+5\left(n+3\right)\right]⋮\left(n+3\right)\)
\(\Rightarrow42⋮\left(n+3\right)\)
\(\Rightarrow\left(n+3\right)\inƯ\left(42\right)=\left\{\pm1;\pm2;\pm3;\pm6;\pm7;\pm14;\pm21;\pm42\right\}\)
\(\Rightarrow n\in\left\{-2;-4;-1;-5;0;-6;3;-9;4;-10;11;-17;18;-24;39;-45\right\}\)
