Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative$$\frac{\frac{2 \left(\sqrt{x} - 2\right)}{\left(x - 3\right)^{2}} - \frac{1}{\sqrt{x} \left(x - 3\right)} - \frac{1}{4 x^{\frac{3}{2}}}}{x - 3} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = \frac{\sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}{2} + \frac{37}{9} + \frac{\sqrt{- \frac{16 \sqrt[3]{3}}{3} + \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{7712}{81} + \frac{503296}{729 \sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}}}{2}$$
You also need to calculate the limits of y '' for arguments seeking to indeterminate points of a function:
Points where there is an indetermination:
$$x_{1} = 3$$
$$\lim_{x \to 3^-}\left(\frac{\frac{2 \left(\sqrt{x} - 2\right)}{\left(x - 3\right)^{2}} - \frac{1}{\sqrt{x} \left(x - 3\right)} - \frac{1}{4 x^{\frac{3}{2}}}}{x - 3}\right) = \infty$$
$$\lim_{x \to 3^+}\left(\frac{\frac{2 \left(\sqrt{x} - 2\right)}{\left(x - 3\right)^{2}} - \frac{1}{\sqrt{x} \left(x - 3\right)} - \frac{1}{4 x^{\frac{3}{2}}}}{x - 3}\right) = -\infty$$
- the limits are not equal, so
$$x_{1} = 3$$
- is an inflection point
Сonvexity and concavity intervals:Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Concave at the intervals
$$\left[\frac{\sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}{2} + \frac{37}{9} + \frac{\sqrt{- \frac{16 \sqrt[3]{3}}{3} + \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{7712}{81} + \frac{503296}{729 \sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}}}{2}, \infty\right)$$
Convex at the intervals
$$\left(-\infty, \frac{\sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}{2} + \frac{37}{9} + \frac{\sqrt{- \frac{16 \sqrt[3]{3}}{3} + \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{7712}{81} + \frac{503296}{729 \sqrt{- \frac{16 \cdot 3^{\frac{2}{3}}}{3} + \frac{16 \sqrt[3]{3}}{3} + \frac{3856}{81}}}}}{2}\right]$$