Evaluate
$\lim _{h \rightarrow 0}\left(\frac{\sqrt{x+h}-\sqrt{x}}{h}\right)$
To evaluate:
$\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}$
Formula used:
L'Hospital's rule
Let $f(x)$ and $g(x)$ be two functions which are differentiable on an open interval $I$ except at a point a where
$\lim _{x \rightarrow a} \mathrm{f}(\mathrm{x})=\lim _{x \rightarrow a} \mathrm{~g}(\mathrm{x})=0$ or $\pm \infty$
then
$\lim _{x \rightarrow a} \frac{\mathrm{f}(\mathrm{x})}{\mathrm{g}(\mathrm{x})}=\lim _{x \rightarrow a} \frac{\mathrm{f}^{\prime}(\mathrm{x})}{\mathrm{g}^{\prime}(\mathrm{x})}$
As $\mathrm{X} \rightarrow 0$, we have
$\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}=\frac{0}{0}$
This represents an indeterminate form. Thus applying L'Hospital's rule, we get
$\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}=\lim _{h \rightarrow 0} \frac{\frac{d}{d h}(\sqrt{x+h}-\sqrt{x})}{\frac{d}{d h}(h)}$
$\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}=\lim _{h \rightarrow 0} \frac{\frac{1}{2 \sqrt{x+h}}}{1}$
$\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}=\frac{1}{2 \sqrt{x}}$
Thus, the value of $\lim _{h \rightarrow 0} \frac{\sqrt{x+h}-\sqrt{x}}{h}$ is $\frac{1}{2 \sqrt{x}}$