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$$\frac{- \frac{2 \left(x \sin{\left(\frac{6}{x} \right)} - 6 \cos{\left(\frac{6}{x} \right)}\right)^{2} \sin^{2}{\left(\frac{6}{x} \right)}}{x^{2} \sin^{2}{\left(\frac{6}{x} \right)} + 1} - \frac{\left(x \sin{\left(\frac{6}{x} \right)} - 6 \cos{\left(\frac{6}{x} \right)}\right)^{2} \sin^{2}{\left(\frac{6}{x} \right)}}{\left(x^{2} \sin^{2}{\left(\frac{6}{x} \right)} + 1\right) \left(\log{\left(x^{2} \sin^{2}{\left(\frac{6}{x} \right)} + 1 \right)} + 1\right)} + \sin^{2}{\left(\frac{6}{x} \right)} - \frac{12 \sin{\left(\frac{6}{x} \right)} \cos{\left(\frac{6}{x} \right)}}{x} - \frac{36 \sin^{2}{\left(\frac{6}{x} \right)}}{x^{2}} + \frac{36 \cos^{2}{\left(\frac{6}{x} \right)}}{x^{2}}}{\left(x^{2} \sin^{2}{\left(\frac{6}{x} \right)} + 1\right) \sqrt{\log{\left(x^{2} \sin^{2}{\left(\frac{6}{x} \right)} + 1 \right)} + 1}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -6086.0924647816$$
$$x_{2} = -2374.22710669979$$
$$x_{3} = 5028.8821338503$$
$$x_{4} = -5431.52156030752$$
$$x_{5} = -5213.3111479491$$
$$x_{6} = 3282.39578083277$$
$$x_{7} = 4374.12997899275$$
$$x_{8} = -10012.5288283993$$
$$x_{9} = -8703.83424043334$$
$$x_{10} = -1936.35591721617$$
$$x_{11} = -9358.19108744458$$
$$x_{12} = -9576.30559718589$$
$$x_{13} = -2155.3796410894$$
$$x_{14} = 4810.64780204567$$
$$x_{15} = 9173.85104799375$$
$$x_{16} = -6958.74823110073$$
$$x_{17} = -6740.59339118704$$
$$x_{18} = 3500.81170699836$$
$$x_{19} = -10666.8509803771$$
$$x_{20} = -4122.03629178067$$
$$x_{21} = 5465.311463932$$
$$x_{22} = 10264.412910112$$
$$x_{23} = 5683.50948564274$$
$$x_{24} = -1.70208058174794$$
$$x_{25} = -10884.955386183$$
$$x_{26} = 7865.09966354048$$
$$x_{27} = -7831.32044258065$$
$$x_{28} = -3903.71929431245$$
$$x_{29} = 8955.7325163623$$
$$x_{30} = 10700.6256276511$$
$$x_{31} = 10918.7298211157$$
$$x_{32} = 7210.67903700561$$
$$x_{33} = -7613.1836509254$$
$$x_{34} = 6338.05074040179$$
$$x_{35} = 2189.27891638134$$
$$x_{36} = 3063.93049789169$$
$$x_{37} = -3466.991964909$$
$$x_{38} = -7395.04293151992$$
$$x_{39} = 4592.3978635999$$
$$x_{40} = -9140.07446404697$$
$$x_{41} = 10482.5200206933$$
$$x_{42} = 8737.61157277058$$
$$x_{43} = -3248.56905481542$$
$$x_{44} = -8267.58348678963$$
$$x_{45} = 7428.82335660464$$
$$x_{46} = 5247.10280858998$$
$$x_{47} = 9391.96733577131$$
$$x_{48} = 2.13910723351709$$
$$x_{49} = 7646.96344812247$$
$$x_{50} = 5901.69805424894$$
$$x_{51} = -5867.91109600783$$
$$x_{52} = -3685.37303246147$$
$$x_{53} = -10448.745147661$$
$$x_{54} = 2626.80242402927$$
$$x_{55} = 2408.10362843824$$
$$x_{56} = 4155.84131604041$$
$$x_{57} = -8921.95557191908$$
$$x_{58} = 6774.37607874084$$
$$x_{59} = -2811.55857587021$$
$$x_{60} = 3937.52841286536$$
$$x_{61} = -8485.71028140802$$
$$x_{62} = 6556.21648653565$$
$$x_{63} = -4776.85187939258$$
$$x_{64} = -4340.3284482294$$
$$x_{65} = 3719.18699238135$$
$$x_{66} = -6522.43288968514$$
$$x_{67} = 8519.4880318858$$
$$x_{68} = 9828.19377753567$$
$$x_{69} = -7176.89792601828$$
$$x_{70} = -5649.72113980702$$
$$x_{71} = 2845.40445274502$$
$$x_{72} = 8301.36168888368$$
$$x_{73} = 8083.23231681613$$
$$x_{74} = 10046.3041979464$$
$$x_{75} = 6992.53009338194$$
$$x_{76} = 6119.87818169326$$
$$x_{77} = -6304.26613841952$$
$$x_{78} = 1970.28607401782$$
$$x_{79} = -9794.41813452438$$
$$x_{80} = 9610.08153253132$$
$$x_{81} = -4995.08848146178$$
$$x_{82} = -10230.6377967493$$
$$x_{83} = -8049.45362595802$$
$$x_{84} = -4558.59933766427$$
$$x_{85} = -2592.9431538878$$
$$x_{86} = -3030.09522788353$$
Además hay que calcular los límites de y'' para los argumentos tendientes a los puntos de indeterminación de la función:
Puntos donde hay indeterminación:
$$x_{1} = 0$$
True
True
- los límites no son iguales, signo
$$x_{1} = 0$$
- 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
$$\left(-\infty, -1.70208058174794\right]$$
Convexa en los intervalos
$$\left[2.13910723351709, \infty\right)$$