2 câu trả lời
`3x + 4 \vdots x - 3`
`x - 3 \vdots x - 3`
`=> [(3x + 4) - 3(x - 3)] \vdots x - 3`
`=> [(3x + 4) - (3x - 9)] \vdots x - 3`
`=> 13 \vdots x - 3`
`=> x - 3 in Ư(13) = {1; -1; 13; -13}`
`=> x - 3 in {1; -1; 13; -13}`
`=> x in {4; 2; 16; -10} `
Vậy `x in {4; 2; 16; -10} `
Ta có: `3x + 4` $\vdots$ `x - 3`
Mà `x - 3` $\vdots$ `x - 3`
`=> (3x + 4) - (x - 3)`$\vdots$ `x - 3`
`=> (3x + 4) - (3x - 9)`$\vdots$ `x - 3`
`=> 3x + 4 - 3x + 9`$\vdots$ `x - 3`
`=> 13` $\vdots$ `x - 3`
`=> x - 3 là Ư(13)`
Ta có bảng sau:
\begin{array}{|c|c|c|}\hline \text{x-3}&\text{1}&\text{-1}&\text{13}&\text{-13}\\\hline \text{x}&\text{4}&\text{2}&\text{16}&\text{-10}\\\hline\end{array}
Vậy `x ∈ { 4; 2; 16; -10 }`
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