Đáp án:
`b, (x-5)(xy+1)=3`
`=> x-5, xy +1 in Ư(3)={±1 ; ±3}`
Có `x; y in ZZ` nên ta có bảng sau :
\begin{array}{|c|c|c|}\hline \text{x-5}&\text{1}&\text{3}&\text{-1}&\text{-3}\\\hline \text{xy +1}&\text{3}&\text{1}&\text{-3}&\text{-1}\\\hline \text{x}&\text{6}&\text{8}&\text{4}&\text{2}\\\hline \text{y}&\text{$\frac{1}{3}$ (KTM)}&\text{0}&\text{-1}&\text{-1}\\\hline\end{array}
Vậy `(x;y)= (8;0)(4; -1)(2; -1)`
