2 câu trả lời
Đáp án:
`(n;m) = {(1;5);(-1;-3);(2;3);(-2;-1);(4;2);(-4;0)}`
Giải thích các bước giải:
`m/2 - 2/n = 1/2`
`=> 2/n = m/2 - 1/2 = m-1/2`
`n . (m - 1) = 2. 2 = 4`
Ta có:
` Ư(4) = {1;-1;2;-2;4;-4}`
Có bảng sau:
\begin{array}{|c|c|c|}\hline \text{n}&\text{1}&\text{-1}&\text{2}&\text{-2}&\text{4}&\text{-4}\\\hline \text{m - 1}&\text{4}&\text{-4}&\text{2}&\text{-2}&\text{1}&\text{-1}\\\hline \text{m}&\text{5}&\text{-3}&\text{3}&\text{-1}&\text{2}&\text{0}\\\hline\end{array}
Vậy, các cặp `(n;m)` là:
`(n;m) = {(1;5);(-1;-3);(2;3);(-2;-1);(4;2);(-4;0)}`
Ta có: `m/2 - 2/n = 1/2`
`=> 2/n = m/2 - 1/2 = (m-1)/2`
`=> n(m - 1) = 2.2`
`=> n(m - 1) = 4`
`=> n,m in Ư(4) = {±1;±2;±4}`
Ta có bảng giá trị sau:
$\begin{array}{|c|c|c|}\hline \text{n}&\text{1}&\text{-1}&\text{2}&\text{-2}&\text{4}&\text{-4}\\\hline \text{m - 1}&\text{4}&\text{-4}&\text{2}&\text{-2}&\text{1}&\text{-1}\\\hline \text{m}&\text{5}&\text{-3}&\text{3}&\text{-1}&\text{2}&\text{0}\\\hline\end{array}$
`text\{Vậy các cặp (n;m) thỏa mãn là: (1;5),(-1;-3),(2;3),(-2;-1),(4;2),(-4;0)}`