Liên hợp nha
* $\lim \dfrac{-n^3 +n^2+2}{\sqrt{n^3 -1}+\sqrt{n^2+1}}=\lim \dfrac{-1+\dfrac{1}{n}+\dfrac{2}{n^3}}{\sqrt{\dfrac{1}{n^3}-\dfrac{1}{n^6}}+\sqrt{\dfrac{1}{n^4}+\dfrac{1}{n^6}}}=-\infty$
* $\lim \limits_{x\to 0} \dfrac{1-\sqrt[3]{1-x}}{2x}=\lim \limits_{x\to 0} \dfrac{x}{2x(1+\sqrt[3]{1-x} +\sqrt[3]{(1-x)^2})}$
$=\lim \limits_{x\to 0} \dfrac{1}{2(1+\sqrt[3]{1-x} +\sqrt[3]{(1-x)^2})}=\dfrac{1}{6}$