Question

$\lim_{n \to \infty} \frac{\sqrt{n^{3}+3 }-\sqrt{n-3} }{\sqrt[5]{n^{5}+3 }+\sqrt{n-3} }$

Answer 1

$\displaystyle \lim_{n \to \infty}\dfrac{\sqrt{n^3+3}-\sqrt{n-3}}{\sqrt[5]{n^5+3}+\sqrt{n-3}}=\lim_{n \to \infty}\dfrac{n\sqrt{n}\cdot \sqrt{1+\dfrac{3}{n^3}}-\sqrt{n}\sqrt{1-\dfrac{3}{n}}}{n\sqrt[5]{1+\dfrac{3}{n^5}}+\sqrt{n}\sqrt{1-\dfrac{3}{n}}}\\ \\ \\ \\ =\lim_{n \to \infty}\dfrac{n\sqrt{n}\left(\sqrt{1+\dfrac{3}{n^3}}-\dfrac{1}{n}\sqrt{1-\dfrac{3}{n}}\right)}{n\left(\sqrt[5]{1+\dfrac{3}{n^5}}+\dfrac{1}{\sqrt{n}}\sqrt{1-\dfrac{3}{n}\right)}}=\lim_{n \to \infty}\dfrac{\sqrt{n}\cdot 1}{1}=\infty$