1. Tìm lim (n^3 - 2n) / (3n^2 + n - 2) 2. Tìm lim (-2 + 3n - 2n^3) / (3n - 2)

1.

$\lim\dfrac{n^3-2n}{3n^2+n-2}$

$=\lim\dfrac{n^3\Big(1-\dfrac{2}{n^2}\Big)}{n^2\Big(3+\dfrac{1}{n}-\dfrac{2}{n^2}\Big)}$

$=\lim n.\dfrac{1-\dfrac{2}{n^2}}{3+\dfrac{1}{n}-\dfrac{2}{n^2}}$

$=+\infty$

2.

$\lim\dfrac{-2+3n-2n^3}{3n-2}$

$=\lim \dfrac{n^3\Big(\dfrac{-2}{n^3}+\dfrac{3}{n^2}-2\Big)}{n\Big(3-\dfrac{2}{n}\Big)}$

$=\lim n^2.\dfrac{\dfrac{-2}{n^3}+\dfrac{3}{n^2}-2}{3-\dfrac{2}{n}}$

$=-\infty$