Question

[Lê Diệu Hiền]

Tìm số nguyên x biết :

a) 0 < / x + 1 / \(\le\) 3

b) 0 < / x / < 3

c) -3 \(\le\) / x + 1 / \(\le\) 3

Answer 1

[.]

a) Ta có : \(0< \left|x+1\right|\le3\)

\(\Rightarrow\left|x+1\right|\in\left\{1;2;3\right\}\)

\(\Rightarrow x+1\in\left\{-1;1;-2;2;-3;3\right\}\)

\(\Rightarrow x\in\left\{-2;0;-3;1;-4;2\right\}\)

b) Ta có : \(0< \left|x\right|< 3\)

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

\(\Rightarrow x\in\left\{\pm1;\pm2\right\}\)

c) Ta có : \(-3\le\left|x+1\right|\le3\)

\(\Rightarrow\left|x+1\right|\in\left\{0;1;2;3\right\}\)

\(\Rightarrow x+1\in\left\{0;-1;1;-2;2;-3;3\right\}\)

\(\Rightarrow x\in\left\{-1;-2;0;-3;1;-4;2\right\}\)