Question

Tìm x,y thuộc Z, biết:

(2x - 1) x (4y + 2) = -30

Answer 1

\(\left(2x-1\right)\left(4y+2\right)=-30\)

\(\Leftrightarrow2x-1;4y+2\inƯ\left(-30\right)\)

Ta có các trường hợp :

+) \(\left\{{}\begin{matrix}2x-1=1\\4y+2=-30\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-8\end{matrix}\right.\)

+) \(\left\{{}\begin{matrix}2x-1=2\\4y+2=-15\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{3}{2}\\-\dfrac{13}{4}\end{matrix}\right.\) \(\left(loại\right)\)

+) \(\left\{{}\begin{matrix}2x-1=3\\4y+2=-10\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=-3\end{matrix}\right.\)

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