Question

Найдите предел lim( √(n^2+1)-√(n^2-1) ) n→+∞

Answer 1

$\displaystyle \lim_{n \to \infty} \big( \sqrt{n^2+1} - \sqrt{n^2-1}\big)= \lim_{n \to \infty} \frac{n^2+1-n^2+1}{ \sqrt{n^2+1}+ \sqrt{n^2-1} }=\\ \\ \\ =2\lim_{n \to \infty} \frac{ \frac{1}{n} }{ \sqrt{1 + \frac{1}{n^2} }+ \sqrt{1- \frac{1}{n^2} } } =0$