Giải thích các bước giải:
$\lim \dfrac{\sqrt{4n-1}}{\sqrt{n}+1}$
$=\lim \dfrac{\sqrt{4-\dfrac{1}{n}}}{1+\dfrac{1}{\sqrt{n}}}$
$=\dfrac{\sqrt{4}}{1}$
$=2$
$\lim \dfrac{n^4}{(n+1)(n+2)(n^2+1)}$
$=\lim \dfrac{1}{(1+\dfrac{1}{n})(1+\dfrac{2}{n})(1+\dfrac{1}{n^2})}$
$=\dfrac{1}{(1+0)(1+0)(1+0)}$
$=1$
$\lim\dfrac{3n^3+2n^2+n}{n^3+4}$
$=\lim\dfrac{3+\dfrac{2}{n}+\dfrac{1}{n^2}}{1+\dfrac{4}{n^3}}$
$=\dfrac{3+0+0}{1+0}$
$=3$
