Question

Tìm x biết:

a. 30-5x chia hết cho x

b. x+20 xhia hết cho x+1

c. 2x+10 chia hết cho 2x+1

ai nhanh mik tick

Answer 1

\(x+20⋮x+1\)

\(\Rightarrow x+1+19⋮x+1\)

mà \(x+1⋮x+1\Rightarrow x+1\inƯ\left(19\right)=\left\{\pm1;\pm19\right\}\)

\(\Rightarrow x\in\left\{0;-2;18;-20\right\}\)

Answer 2

\(2x+10⋮2x+1\)

\(\Rightarrow2x+1+9⋮2x+1\)

\(\Rightarrow2x+1⋮2x+1\Rightarrow2x+1\inƯ\left(9\right)=\left\{\pm1;\pm3;\pm9\right\}\)

2x + 1 = 1 => x = 0

2x +  1 = -1 => x= -1 

.... tương tự 

Answer 3

\(30-5x⋮x\)

mà \(5x⋮x\Rightarrow x\inƯ\left(30\right)=\left\{\pm1;\pm2;\pm3;\pm5;\pm6;\pm10;\pm30\right\}\)

bn tự lập nha !