n2+3⋮n+1
Mà n+1⋮n+1
\(\Leftrightarrow\left\{{}\begin{matrix}n^2+3⋮n+1\^2+1⋮n+1\end{matrix}\right.\)
⇔2⋮n+1
⇔n+1∈Ư(2)
\(\Leftrightarrow\left[{}\begin{matrix}n+1=1\+1=2\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}n=0\=1\end{matrix}\right.\)
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