Tìm `x`, biết, `10x+23\vdots2x+1`

`10x+23`$\vdots$`2x+1`

`=>10x+23-5(2x+1)`$\vdots$`2x+1`

`=>10x+23-10x-5`$\vdots$`2x+1`

`=>18`$\vdots$`2x+1`

`=>2x+1in Ư(18)={+-1;+-2;+-3;+-6;+-9;+-18}`

Mà `2x+1` là số lẻ

`=>2x+1in {+-1;+-3;+-9}`

Ta có bảng sau:

\begin{array}{|c|c|c|c|c|c|c|}\hline \text{$2x+1$}&\text{1}&\text{$-1$}&\text{3}&\text{$-3$}&\text{9}&\text{$-9$}\\\hline \text{$2x$}&\text{0}&\text{$-2$}&\text{2}&\text{$-4$}&\text{8}&\text{$-10$}\\\hline \text{$x$}&\text{0}&\text{$-1$}&\text{1}&\text{$-2$}&\text{4}&\text{$-5$}\\\hline\end{array}

Vậy `x in {0;-1;1;-2;4;-5}`