\lim \limits_{x\to -\infty} \dfrac{\sqrt{x^2+2x+3}}{x+1}
=\lim \limits_{x\to -\infty} \dfrac{-x\sqrt{1+\dfrac{2}{x}+\dfrac{3}{x^2}}}{x(1+\dfrac{1}x)}=\lim \limits_{x\to -\infty} \dfrac{-\sqrt{1+\dfrac{2}{x}+\dfrac{3}{x^2}}}{1+\dfrac{1}x}=-1
Em tham khảo nhé