lim (n - $\sqrt{n²+2n-3}$)
= lim $\frac{n²-n²-2n+3}{n+\sqrt{n²+2n-3}}$
= lim $\frac{3-2n}{n(1+\sqrt{1+2/n-3/n²})}$
= lim $\frac{n(3/n - 2)}{n(1+\sqrt{1+2/n-3/n²})}$
= lim $\frac{3/n - 2}{1+\sqrt{1+2/n-3/n²}}$
= lim $\frac{0 - 2}{1+\sqrt{1+0-0}}$
= lim $\frac{-2}{2}$
= -1
Vậy lim (n - $\sqrt{n²+2n-3}$) = -1