Question

Tìm x, y\(\in\) Z để:

a) \(\frac{4}{x}\in Z\)b) \(\frac{7}{x-1}\in Z\)

Answer 1

a) \(x\inƯ\left(4\right)=\left\{-4;-2;-1;1;2;4\right\}\)

b) \(x-1\inƯ\left(7\right)=\left\{-7;-1;1;7\right\}\)

\(\Leftrightarrow x\in\left\{-6;0;2;8\right\}\)

Answer 2

a) \(\frac{4}{x}\)ϵ Z ↔ 4 chia hết cho x

→ x ϵ Ư( 4 ) = { -4 ; -2 ; -1 ; 1 ; 2 ; 4 }

b) \(\frac{7}{x-1}\) ϵ Z ↔ 7 chia hết cho x

→ x ϵ Ư( 7 ) = { -6 ; 0 ; 2 ; 8 }