\(lim\dfrac{\sqrt{n^3+1}-1}{n^2+1}\\ =lim\dfrac{\sqrt{\dfrac{n^3}{n^3}+\dfrac{1}{n^3}}-\dfrac{1}{n^3}}{n^2\left(1+\dfrac{1}{n^2}\right)}\\ =lim\dfrac{n\sqrt{n}.\left(\sqrt{1+\dfrac{1}{n^3}}-\dfrac{1}{n^3}\right)}{n\sqrt{n^2}\left(1+\dfrac{1}{n^2}\right)}\\ =lim\dfrac{1}{\sqrt{n}}.\dfrac{\sqrt{1+\dfrac{1}{n^3}}-\dfrac{1}{n^3}}{1+\dfrac{1}{n^2}}\\ =0\)