Question

Answer 1

a: Để A là số nguyên thì \(n+1\in\left\{1;-1;5;-5\right\}\)

hay \(n\in\left\{0;-2;4;-6\right\}\)

b: Để B nguyên thì \(2n-1\in\left\{1;-1;3;-3\right\}\)

\(\Leftrightarrow2n\in\left\{2;0;4;-2\right\}\)

hay \(n\in\left\{1;0;2;-1\right\}\)

Answer 2

\(A=\dfrac{3\left(n+1\right)-5}{n+1}=3-\dfrac{5}{n+1}\in Z\\ \Leftrightarrow5⋮n+1\Leftrightarrow n+1\inƯ\left(5\right)=\left\{-5;-1;1;5\right\}\\ \Leftrightarrow n\in\left\{-6;-2;0;4\right\}\)