Question

Cho \(A=\frac{5}{x-2}\). Tìm x để A nguyên

Answer 1

Giải:

Để \(A\in Z\)

\(\Rightarrow5⋮x-2\)

\(\Rightarrow x-2\in\left\{1;-1;5;-5\right\}\)

+) \(x-2=1\Rightarrow x=3\)

+) \(x-2=-1\Rightarrow x=1\)

+) \(x-2=5\Rightarrow x=7\)

+) \(x-2=-5\Rightarrow x=-3\)

Vậy \(x\in\left\{3;1;7;-3\right\}\)