Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(la segunda derivada es igual a cero),
las raíces de la ecuación obtenida serán los puntos de flexión para el gráfico de la función indicado:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
segunda derivada$$\frac{\sqrt{- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)}} \left(- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - \frac{\left(x - 5\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right) \left(x - 3\right)^{2}} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right)^{2} \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right)}{2} + 1 + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 2\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 4\right)} - \frac{\left(x - 2\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 5\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right) \left(2 x - \left(x - 5\right) \left(x - 2\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right) - 7\right)}{4 \left(x - 5\right) \left(x - 2\right)}\right)}{\left(x - 5\right) \left(x - 2\right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = \frac{7}{2} - \sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}}$$
$$x_{2} = \sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}} + \frac{7}{2}$$
Además hay que calcular los límites de y'' para los argumentos tendientes a los puntos de indeterminación de la función:
Puntos donde hay indeterminación:
$$x_{1} = 3$$
$$x_{2} = 4$$
$$\lim_{x \to 3^-}\left(\frac{\sqrt{- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)}} \left(- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - \frac{\left(x - 5\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right) \left(x - 3\right)^{2}} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right)^{2} \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right)}{2} + 1 + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 2\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 4\right)} - \frac{\left(x - 2\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 5\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right) \left(2 x - \left(x - 5\right) \left(x - 2\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right) - 7\right)}{4 \left(x - 5\right) \left(x - 2\right)}\right)}{\left(x - 5\right) \left(x - 2\right)}\right) = \infty$$
$$\lim_{x \to 3^+}\left(\frac{\sqrt{- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)}} \left(- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - \frac{\left(x - 5\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right) \left(x - 3\right)^{2}} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right)^{2} \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right)}{2} + 1 + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 2\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 4\right)} - \frac{\left(x - 2\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 5\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right) \left(2 x - \left(x - 5\right) \left(x - 2\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right) - 7\right)}{4 \left(x - 5\right) \left(x - 2\right)}\right)}{\left(x - 5\right) \left(x - 2\right)}\right) = \infty i$$
- los límites no son iguales, signo
$$x_{1} = 3$$
- es el punto de flexión
$$\lim_{x \to 4^-}\left(\frac{\sqrt{- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)}} \left(- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - \frac{\left(x - 5\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right) \left(x - 3\right)^{2}} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right)^{2} \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right)}{2} + 1 + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 2\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 4\right)} - \frac{\left(x - 2\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 5\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right) \left(2 x - \left(x - 5\right) \left(x - 2\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right) - 7\right)}{4 \left(x - 5\right) \left(x - 2\right)}\right)}{\left(x - 5\right) \left(x - 2\right)}\right) = \infty i$$
$$\lim_{x \to 4^+}\left(\frac{\sqrt{- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)}} \left(- \frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - \frac{\left(x - 5\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right) \left(x - 3\right)^{2}} + \frac{\left(x - 5\right) \left(x - 2\right) \left(2 x - 7\right)}{\left(x - 4\right)^{2} \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right)}{2} + 1 + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 2\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 3\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 4\right)} - \frac{\left(x - 2\right) \left(2 x - 7\right)}{2 \left(x - 4\right) \left(x - 3\right)} + \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right)}{2 \left(x - 5\right)} - \frac{\left(2 x - 7\right) \left(\frac{\left(x - 5\right) \left(x - 2\right)}{\left(x - 4\right) \left(x - 3\right)} - 1\right) \left(2 x - \left(x - 5\right) \left(x - 2\right) \left(\frac{1}{x - 3} + \frac{1}{x - 4}\right) - 7\right)}{4 \left(x - 5\right) \left(x - 2\right)}\right)}{\left(x - 5\right) \left(x - 2\right)}\right) = \infty$$
- los límites no son iguales, signo
$$x_{2} = 4$$
- es el punto de flexión
Intervalos de convexidad y concavidad:Hallemos los intervales donde la función es convexa o cóncava, para eso veamos cómo se comporta la función en los puntos de flexiones:
Cóncava en los intervalos
$$\left[\frac{7}{2} - \sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}}, \sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}} + \frac{7}{2}\right]$$
Convexa en los intervalos
$$\left(-\infty, \frac{7}{2} - \sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}}\right] \cup \left[\sqrt{\frac{3}{4} + \frac{\sqrt{3}}{2}} + \frac{7}{2}, \infty\right)$$