2) $lim(\sqrt{4n^2+4n}-2n)$
$=lim\frac{(4n^2+4n)-(2n)^2}{\sqrt{4n^2+4n}+2n}$
$=lim\frac{4n}{\sqrt{4n^2+4n}+2n}$
$=lim\frac{4}{\sqrt{4+\frac{4}{n}}+2} $
$=\frac{4}{\sqrt{4}+2}=1$
4) $lim\frac{2(\frac{3}{5})^n+1}{1+(\frac{3}{5})^n}$
Vì $\frac{3}{5}<1⇒lim\frac{3}{5})^n=0$
⇒$lim\frac{2(\frac{3}{5})^n+1}{1+(\frac{3}{5})^n}=\frac{2.0+1}{1+0}=1$