\[\boxed{\text{89\ (89).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ \frac{n + 6}{n} = \frac{n}{n} + \frac{6}{n} = 1 + \frac{6}{n} \Longrightarrow\]
\[\Longrightarrow целое\ \ при\ n = 1,\ 2,\ 3,\ 6.\]
\[2)\ \frac{3n^{2} - 4n - 14}{n} =\]
\[= \frac{3n^{2}}{n} - \frac{4n}{n} - \frac{14}{n} =\]
\[= 3n - 4 - \frac{14}{n} \Longrightarrow\]
\[целое,\ при\ n = 1,\ 2,\ 7,\ 14\]
\[3)\frac{4n + 7}{2n - 3} = \frac{4n - 6 + 13}{2n - 3} =\]
\[= \frac{4n - 6}{2n - 3} + \frac{13}{2n - 3} =\]
\[= \frac{2 \cdot (2n - 3)}{2n - 3} + \frac{13}{2n - 3} =\]
\[= 2 + \frac{13}{2n - 3} \Longrightarrow целое\ при\ n =\]
\[= 1,\ 2,\ 8.\]