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$$\frac{\left(\frac{2 \left(x + 1\right) e^{x}}{x e^{x} + 1} - 1 + \frac{\left(x - \frac{2 \left(x + 1\right)^{2} e^{x}}{x e^{x} + 1} + 2\right) e^{x}}{x e^{x} + 1}\right) e^{x}}{x e^{x} + 1} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 33122.2351429581$$
$$x_{2} = -36.8719912319021$$
$$x_{3} = 40750.6632690734$$
$$x_{4} = -116.872003083$$
$$x_{5} = 19560.6043923517$$
$$x_{6} = -60.8720030830002$$
$$x_{7} = -106.872003083$$
$$x_{8} = -48.8720030828669$$
$$x_{9} = -66.8720030830002$$
$$x_{10} = -72.8720030830002$$
$$x_{11} = -92.8720030830002$$
$$x_{12} = 31427.029551779$$
$$x_{13} = 36512.6471277453$$
$$x_{14} = -80.8720030830002$$
$$x_{15} = -102.872003083$$
$$x_{16} = -86.8720030830002$$
$$x_{17} = -78.8720030830002$$
$$x_{18} = 28884.2217989658$$
$$x_{19} = 22951.007978446$$
$$x_{20} = -64.8720030830002$$
$$x_{21} = 35665.0440431628$$
$$x_{22} = 30579.4268759524$$
$$x_{23} = 42445.8700073105$$
$$x_{24} = -40.8720028058391$$
$$x_{25} = -94.8720030830002$$
$$x_{26} = 11932.2240708463$$
$$x_{27} = 16170.2064066253$$
$$x_{28} = -108.872003083$$
$$x_{29} = -68.8720030830002$$
$$x_{30} = 14475.0107433807$$
$$x_{31} = -110.872003083$$
$$x_{32} = -34.8719276380146$$
$$x_{33} = -38.8720012570845$$
$$x_{34} = 39903.0599551918$$
$$x_{35} = -118.872003083$$
$$x_{36} = -50.8720030829808$$
$$x_{37} = 26341.415002707$$
$$x_{38} = -114.872003083$$
$$x_{39} = 20408.2048728529$$
$$x_{40} = 28036.6194144112$$
$$x_{41} = -32.8715352046106$$
$$x_{42} = -74.8720030830002$$
$$x_{43} = 13627.4141064976$$
$$x_{44} = -62.8720030830002$$
$$x_{45} = -88.8720030830002$$
$$x_{46} = -84.8720030830002$$
$$x_{47} = 12779.8184773785$$
$$x_{48} = -120.872003083$$
$$x_{49} = -44.872003076823$$
$$x_{50} = -112.872003083$$
$$x_{51} = 17017.8051950062$$
$$x_{52} = -100.872003083$$
$$x_{53} = 37360.2502645683$$
$$x_{54} = -30.8692080757983$$
$$x_{55} = 38207.8534501551$$
$$x_{56} = 25493.8129993199$$
$$x_{57} = 29731.8242890716$$
$$x_{58} = -46.8720030820897$$
$$x_{59} = -82.8720030830002$$
$$x_{60} = 41598.2666205299$$
$$x_{61} = -70.8720030830002$$
$$x_{62} = 15322.6082208076$$
$$x_{63} = -52.8720030829974$$
$$x_{64} = -54.8720030829998$$
$$x_{65} = -98.8720030830002$$
$$x_{66} = 17865.4045002026$$
$$x_{67} = -58.8720030830002$$
$$x_{68} = 24646.2111494747$$
$$x_{69} = 0.765591842440394$$
$$x_{70} = 32274.6323095441$$
$$x_{71} = -42.8720030414237$$
$$x_{72} = -56.8720030830001$$
$$x_{73} = 23798.6094695748$$
$$x_{74} = 21255.8056528181$$
$$x_{75} = -28.856245022617$$
$$x_{76} = 27189.0171452781$$
$$x_{77} = -90.8720030830002$$
$$x_{78} = 34817.4410146354$$
$$x_{79} = 39055.4566813312$$
$$x_{80} = 33969.8380463588$$
$$x_{81} = -96.8720030830002$$
$$x_{82} = -104.872003083$$
$$x_{83} = 22103.4066978018$$
$$x_{84} = -76.8720030830002$$
$$x_{85} = 18713.004252$$
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
$$\left(-\infty, 0.765591842440394\right]$$
Convexa en los intervalos
$$\left[0.765591842440394, \infty\right)$$