a/ \(-7⋮2n+1\)
\(\Leftrightarrow2n+1\inƯ\left(-7\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}2n+1=1\\2n+1=7\\2n+1=-1\\2n+1=-7\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}n=0\=3\=-1\=-3\end{matrix}\right.\)
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b/ \(-11⋮2n+5\)
\(\Leftrightarrow2n+5\inƯ\left(-11\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}2n+5=1\\2n+5=11\\2n+5=-1\\2n+5=-11\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}n=-2\=3\=-3\=-8\end{matrix}\right.\)
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