Question

Tìm \(x\in Z\) để \(\dfrac{2x-1}{x+1}\) nguyên

Answer 1

Ta có: 2x - 1 = 2(x + 1) - 3

Để (2x - 1)/(x + 1) nguyên thì 3 ⋮ (x + 1)

⇒ x + 1 ∈ Ư(3) = {-3; -1; 1; 3}

⇒ x ∈ {-4; -2; 0; 2}

Answer 2