Question

Tìm các số nguyên x, sao cho: 2x – 3 là bội của x + 1

Answer 1

\(\Leftrightarrow x+1\in\left\{1;-1;5;-5\right\}\)

hay \(x\in\left\{0;-2;4;-6\right\}\)

Answer 2

\(\Rightarrow2\left(x+1\right)-5⋮\left(x+1\right)\\ \Rightarrow5⋮\left(x+1\right)\\ \Rightarrow x+1\inƯ\left(5\right)=\left\{-5;-1;1;5\right\}\\ \Rightarrow x\in\left\{-6;-2;0;4\right\}\)