a) \(\Leftrightarrow\left(3n-1\right)\inƯ\left(12\right)=\left\{\pm1;\pm2;\pm3;\pm4;\pm6;\pm12;\right\}\)

Tự xét nha

b) \(\Leftrightarrow2\left(n-2\right)⋮7\)

mà (2,7)=1

\(\Rightarrow\left(n-2\right)⋮7\)

\(\Rightarrow n-2=7k\left(k\in Z\right)\)

\(\Rightarrow n=7k+2\)

\(=-21,26-566.72=-587,98\)

Lời giải:
$(-2,3).(-4,56)=2,3.4,56=10,488$

\(=2,3.4,56=10,488\)

\(\left(2n+7\right)⋮\left(2n+1\right)\)

\(\left[\left(2n+1\right)+6\right]⋮\left(2n+1\right)\)

\(\Rightarrow\left(2n+1\right)\inƯ\left(6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)

Còn lại tự xét nha

cau trả lời là còn cái nịt. có tay có chân sao ko làm bài thì dễ mà ko biết mần 

`Answer:`

a) `5x – 100,005 = 4x – 0,005`

`<=>5x-4x=-0,005+100,005`

`<=>x=100`

b) `(2,35 + 5,47) + x = 2x – 40,02`

`<=>7,82+x=2x-40,02`

`<=>x-2x=-40,02-7,82`

`<=>-x=-47,84`

`<=>x=47,84`

c) `x – (303,03 – 103,03) = 405,16`

`<=>x-200=405,26`

`<=>x=405,16+200`

`<=>605,16`

d) `2x + (- 54,05) = x – 45,07`

`<=>2x-54,05=x-45,07`

`<=>2x-x=-45,07+54,05`

`<=>x=8,98`

+) \(\left(2x-3\right)^2=81\)

\(\Rightarrow\left[{}\begin{matrix}2x-3=9\\2x-3=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-3\end{matrix}\right.\)

+) \(\left(x+\dfrac{1}{2}\right)^2=25\)

\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=5\\x+\dfrac{1}{2}=-5\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{9}{2}\\x=-\dfrac{11}{2}\end{matrix}\right.\)