$\Large \underset{x\rightarrow +\infty}{lim}(\sqrt{x+1}-\sqrt{x-3})$ b

$\Large \underset{x\rightarrow +\infty}{lim}(\sqrt{x+1}-\sqrt{x-3})$ bằng

• A.

  0.

• B.

  2.

• C.

  $\Large -\infty$.

• D.

  $\Large +\infty$.

$\Large \underset{x\rightarrow +\infty}{lim}(\sqrt{x+1}-\sqrt{x-3})$ $\Large =\underset{x\rightarrow +\infty}{lim}\dfrac{x+1-(x-3)}{\sqrt{x+1}+\sqrt{x-3}}$$\Large =\underset{x\rightarrow +\infty}{lim}\dfrac{4}{\sqrt{x}\left(\sqrt{1+\dfrac{1}{x}}+\sqrt{1-\dfrac{3}{x}}\right)}=0$.

Chọn đáp án A.