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$$\frac{\left(\tan^{2}{\left(x \right)} + 1\right) \left(\frac{\sqrt{2} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{\frac{3}{2}}{\left(x \right)}} - 4 \sqrt{\tan{\left(x \right)}} + \frac{4 \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{4 \left(2 \tan{\left(x \right)} + 1\right)} + \frac{2 \left(\tan{\left(x \right)} - \frac{\tan^{2}{\left(x \right)} + 1}{\tan{\left(x \right)} - 1}\right) \operatorname{atan}{\left(\sqrt{2 \tan{\left(x \right)}} \right)}}{\tan{\left(x \right)} - 1} + \frac{\sqrt{2} \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(\tan{\left(x \right)} - 1\right) \left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{\tan{\left(x \right)} - 1} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -37.9018316439784$$
$$x_{2} = 81.8584815483035$$
$$x_{3} = 86.3647767666273$$
$$x_{4} = 15.8850358229178$$
$$x_{5} = -31.2388539809291$$
$$x_{6} = 92.6479620738068$$
$$x_{7} = -87.7875217455454$$
$$x_{8} = -81.8841287942355$$
$$x_{9} = -6.10611275221076$$
$$x_{10} = 31.5929990908668$$
$$x_{11} = 28.0716140814072$$
$$x_{12} = 64.3736281914987$$
$$x_{13} = 22.1682211300974$$
$$x_{14} = -23.5909661090155$$
$$x_{15} = 88.141666855483$$
$$x_{16} = -94.070707052725$$
$$x_{17} = -34.3804466345189$$
$$x_{18} = 42.3824796163701$$
$$x_{19} = -50.0884099024679$$
$$x_{20} = -89.5644118344012$$
$$x_{21} = -83.2812265272216$$
$$x_{22} = -56.3715952096474$$
$$x_{23} = 44.1593697052259$$
$$x_{24} = 50.0627626565358$$
$$x_{25} = -100.353892359905$$
$$x_{26} = -12.3892980593903$$
$$x_{27} = -15.9106830688499$$
$$x_{28} = -43.8052245952883$$
$$x_{29} = -45.5821146841441$$
$$x_{30} = -9.62749776167028$$
$$x_{31} = 75.5752962411239$$
$$x_{32} = -28.0972613273393$$
$$x_{33} = -76.998041220042$$
$$x_{34} = 56.3459479637154$$
$$x_{35} = 53.5841476659953$$
$$x_{36} = -21.8140760201597$$
$$x_{37} = -72.0795584775964$$
$$x_{38} = -61.290077952093$$
$$x_{39} = 6.08046550627869$$
$$x_{40} = 59.8673329731749$$
$$x_{41} = -59.892980219107$$
$$x_{42} = 100.328245113972$$
$$x_{43} = 72.0539112316643$$
$$x_{44} = -65.7963731704168$$
$$x_{45} = 94.0450598067929$$
$$x_{46} = 9.60185051573821$$
$$x_{47} = 97.5664448162524$$
$$x_{48} = 78.3370965388439$$
$$x_{49} = 66.1505182803545$$
$$x_{50} = 26.6745163484212$$
$$x_{51} = 37.8761843980463$$
$$x_{52} = -39.2989293769645$$
$$x_{53} = 34.3547993885868$$
$$x_{54} = 70.6568134986783$$
$$x_{55} = 4.68336777329263$$
$$x_{56} = -78.362743784776$$
$$x_{57} = 12.3636508134583$$
$$x_{58} = -1.59981753388696$$
$$x_{59} = 20.3913310412416$$
$$x_{60} = -17.3077808018359$$
$$x_{61} = -67.5732632592726$$
$$x_{62} = 48.6656649235497$$
Además hay que calcular los límites de y'' para los argumentos tendientes a los puntos de indeterminación de la función:
Puntos donde hay indeterminación:
$$x_{1} = 0.785398163397448$$
$$\lim_{x \to 0.785398163397448^-}\left(\frac{\left(\tan^{2}{\left(x \right)} + 1\right) \left(\frac{\sqrt{2} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{\frac{3}{2}}{\left(x \right)}} - 4 \sqrt{\tan{\left(x \right)}} + \frac{4 \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{4 \left(2 \tan{\left(x \right)} + 1\right)} + \frac{2 \left(\tan{\left(x \right)} - \frac{\tan^{2}{\left(x \right)} + 1}{\tan{\left(x \right)} - 1}\right) \operatorname{atan}{\left(\sqrt{2 \tan{\left(x \right)}} \right)}}{\tan{\left(x \right)} - 1} + \frac{\sqrt{2} \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(\tan{\left(x \right)} - 1\right) \left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{\tan{\left(x \right)} - 1}\right) = 1.08172851219476 \cdot 10^{32} \sqrt{2} + 5.84600654932361 \cdot 10^{48} \operatorname{atan}{\left(1 \sqrt{2} \right)}$$
$$\lim_{x \to 0.785398163397448^+}\left(\frac{\left(\tan^{2}{\left(x \right)} + 1\right) \left(\frac{\sqrt{2} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{\frac{3}{2}}{\left(x \right)}} - 4 \sqrt{\tan{\left(x \right)}} + \frac{4 \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{4 \left(2 \tan{\left(x \right)} + 1\right)} + \frac{2 \left(\tan{\left(x \right)} - \frac{\tan^{2}{\left(x \right)} + 1}{\tan{\left(x \right)} - 1}\right) \operatorname{atan}{\left(\sqrt{2 \tan{\left(x \right)}} \right)}}{\tan{\left(x \right)} - 1} + \frac{\sqrt{2} \left(\tan^{2}{\left(x \right)} + 1\right)}{\left(\tan{\left(x \right)} - 1\right) \left(2 \tan{\left(x \right)} + 1\right) \sqrt{\tan{\left(x \right)}}}\right)}{\tan{\left(x \right)} - 1}\right) = 1.08172851219476 \cdot 10^{32} \sqrt{2} + 5.84600654932361 \cdot 10^{48} \operatorname{atan}{\left(1 \sqrt{2} \right)}$$
- los límites son iguales, es decir omitimos el punto correspondiente
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
$$\left[97.5664448162524, \infty\right)$$
Convexa en los intervalos
$$\left(-\infty, -100.353892359905\right]$$