[Toán 8] Phân thức

Q

quynhsieunhan

Có: $A = \frac{2n^3 + n^2 + 7n + 1}{2n - 1} = n^2 + n + 4 + \frac{5}{2n - 1}$
A nguyên \Leftrightarrow $\frac{5}{2n - 1}$ nguyên \Leftrightarrow $\left\{ \begin{array}{l} 2n - 1 = 5 \\ 2n - 1 = -5 \\ 2n - 1 = 1 \\ 2n - 1 = -1 \end{array} \right.$
 
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