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$$\frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)} + \frac{4 x \tan{\left(x \right)}}{\left(2 x - 1\right)^{2}} + \tan^{2}{\left(x \right)} + 1 - \frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) + \tan{\left(x \right)}\right)}{2 x - 1}\right)}{2 x - 1} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 81.681484396398$$
$$x_{2} = -72.256535923608$$
$$x_{3} = -40.840408349035$$
$$x_{4} = -69.1149344596469$$
$$x_{5} = 43.9825585901172$$
$$x_{6} = -65.9733317122516$$
$$x_{7} = 40.841007972091$$
$$x_{8} = 53.4072520620622$$
$$x_{9} = 3.19825709173739$$
$$x_{10} = 65.9735614786747$$
$$x_{11} = -12.5633233387075$$
$$x_{12} = 25.1335487888607$$
$$x_{13} = 84.8230715520839$$
$$x_{14} = -91.1061270442611$$
$$x_{15} = 18.8510011660026$$
$$x_{16} = -25.1319650267853$$
$$x_{17} = -43.9820415787738$$
$$x_{18} = -31.4154278430901$$
$$x_{19} = 78.539897915767$$
$$x_{20} = -3.09615070207739$$
$$x_{21} = -75.3981363128467$$
$$x_{22} = -37.6987646288618$$
$$x_{23} = -81.6813345073808$$
$$x_{24} = -53.4069014390895$$
$$x_{25} = -62.8317274194706$$
$$x_{26} = 21.9922063631948$$
$$x_{27} = -56.5485127739068$$
$$x_{28} = 31.4164413094763$$
$$x_{29} = -34.5571064636535$$
$$x_{30} = 37.6994683712593$$
$$x_{31} = 97.3894252497785$$
$$x_{32} = -97.3893198139283$$
$$x_{33} = -78.5397357953116$$
$$x_{34} = -21.9901375328361$$
$$x_{35} = -100.530915686409$$
$$x_{36} = 15.7100554579033$$
$$x_{37} = 94.2478361973559$$
$$x_{38} = -28.2737192713737$$
$$x_{39} = -94.2477236150974$$
$$x_{40} = 75.3983122254041$$
$$x_{41} = 91.106247524918$$
$$x_{42} = 69.1151438118728$$
$$x_{43} = -84.8229325607255$$
$$x_{44} = 34.5579440029172$$
$$x_{45} = 9.43071057200153$$
$$x_{46} = 87.9646592878671$$
$$x_{47} = 50.2656823362254$$
$$x_{48} = 12.5696654284358$$
$$x_{49} = 47.1241173733308$$
$$x_{50} = 56.548825517996$$
$$x_{51} = 28.2749705374086$$
$$x_{52} = -50.2652865113154$$
$$x_{53} = 59.6904019366911$$
$$x_{54} = -59.6901212489434$$
$$x_{55} = 100.531014635323$$
$$x_{56} = -47.1236670064473$$
$$x_{57} = 6.29685008941474$$
$$x_{58} = -87.9645300474923$$
$$x_{59} = 72.2567274661935$$
$$x_{60} = -9.41942382453209$$
$$x_{61} = -6.27139123531876$$
$$x_{62} = -18.8481847532752$$
$$x_{63} = -15.7059986381021$$
$$x_{64} = 62.8319807384374$$
Además hay que calcular los límites de y'' para los argumentos tendientes a los puntos de indeterminación de la función:
Puntos donde hay indeterminación:
$$x_{1} = 0.5$$
$$\lim_{x \to 0.5^-}\left(\frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)} + \frac{4 x \tan{\left(x \right)}}{\left(2 x - 1\right)^{2}} + \tan^{2}{\left(x \right)} + 1 - \frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) + \tan{\left(x \right)}\right)}{2 x - 1}\right)}{2 x - 1}\right) = -\infty$$
$$\lim_{x \to 0.5^+}\left(\frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)} + \frac{4 x \tan{\left(x \right)}}{\left(2 x - 1\right)^{2}} + \tan^{2}{\left(x \right)} + 1 - \frac{2 \left(x \left(\tan^{2}{\left(x \right)} + 1\right) + \tan{\left(x \right)}\right)}{2 x - 1}\right)}{2 x - 1}\right) = \infty$$
- los límites no son iguales, signo
$$x_{1} = 0.5$$
- 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
$$\left[100.531014635323, \infty\right)$$
Convexa en los intervalos
$$\left(-\infty, -100.530915686409\right]$$