Question

Tìm x\(\in\)N, để cho:

a, (n+8)\(⋮\) (n+5)

b, (16-3n)\(⋮\)(n+4)

Mik đag cần gấp, giúp mik vs ạ

Answer 1

Để \(\left(n+8\right)⋮\left(n+5\right)\) thì

\(\left(n+8\right)-\left(n+5\right)⋮\left(n+5\right)\)

\(\Rightarrow\)\(3⋮\left(n+5\right)\)

\(\Rightarrow\)​​\(\left(n+5\right)\inƯ\left(3\right)\)

\(\Rightarrow\)\(\left(n+5\right)\in\left(1;-1;3;-3\right)\)

\(\Rightarrow\)\(n\in\left(-4;-6;-2;-8\right)\)

Answer 2

Để \(\left(16-3n\right)⋮\left(n+4\right)\) thì

\(\left(16-3n\right)+\left(n+4\right)⋮\left(n+4\right)\)

\(\Rightarrow\)\(\left(16-3n\right)+3\left(n+4\right)⋮\left(n+4\right)\)

\(\Rightarrow\)\(16-3n+3n+12⋮\left(n+4\right)\)

\(\Rightarrow\)\(28⋮\left(n+4\right)\)

\(\Rightarrow\)\(\left(n+4\right)\inƯ\left(28\right)\)

\(\Rightarrow\)\(\left(n+4\right)\in\left\{\pm1;\pm2;\pm4;\pm7;\pm14;\pm28\right\}\)

\(\Rightarrow\)\(n\in\left\{-3;-4;-2;-6;0;-8;3;-11;10;-18;24;-32\right\}\)

Answer 3

Phần a, 2 dòng cuối lỗi tí 

\(\left(n+5\right)\in\left\{1;-1;3;-3\right\}\)

\(n\in\left\{-4;-6;-2;-8\right\}\)