Question

Bài 3: Tìm số x thuộc Z biết:

\(a,30⋮xvã< 8\)b,\(70⋮x,84⋮xvax>8\)

Answer 1

a) \(30⋮x\Rightarrow x\inƯ\left(30\right)\Rightarrow x\in\left\{\pm1;\pm2;\pm3;\pm5;\pm6;\pm10;\pm15\pm30\right\}\)

Mà x < 8\(\Rightarrow x\in\left\{\pm1;\pm2;\pm3;\pm5;\pm6\right\}\)

b) \(70⋮x,84⋮x\Rightarrow x\inƯC\left(70;84\right)\)

\(\Rightarrow x\in\left\{\pm1;\pm2;\pm7;\pm14\right\}\)

Mà x > 8 \(\Rightarrow x=14\).

Answer 2

câu a thiếu, phải là : x\(=\left\{\pm1;\pm2;\pm3;\pm5;\pm6;-10;-15;-30\right\}\)