Question

Tìm x thuộc Z để 2/1-2x thuộc Z

Answer 1

`2/(1-2x) in ZZ`

`-> 2 vdots 1 -2x`

`-> 1 - 2x in Ư(2)`

Vì `1 - 2x cancel vdots 2`

`-> 1 - 2x in {+-1}`

`-> x in {0, 1}`

Answer 2

Vì \(\dfrac{2}{1-2x}\in Z\Rightarrow2⋮1-2x\Rightarrow1-2x\in\left\{-2,-1,1,2\right\}\Rightarrow x\in\left\{1,0\right\}\) (vì \(x\in Z\))

Vậy x ∈ {1,0}