Para hallar los extremos hay que resolver la ecuación
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
$$\frac{d}{d x} f{\left(x \right)} = $$
primera derivada$$- \frac{6 \sqrt{x} \tanh^{2}{\left(x \right)} \operatorname{acot}{\left(3 x \right)}}{9 x^{2} + 1} + \left(\sqrt{x} \left(2 - 2 \tanh^{2}{\left(x \right)}\right) \tanh{\left(x \right)} + \frac{\tanh^{2}{\left(x \right)}}{2 \sqrt{x}}\right) \operatorname{acot}^{2}{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -35313.9547446642$$
$$x_{2} = -108665.095446708$$
$$x_{3} = 97200.3230699824$$
$$x_{4} = -54242.6728820705$$
$$x_{5} = -44778.1854046872$$
$$x_{6} = -75538.2086602841$$
$$x_{7} = -63707.302711128$$
$$x_{8} = 113763.830381841$$
$$x_{9} = 45144.4655947252$$
$$x_{10} = -115763.750986489$$
$$x_{11} = 56975.1082427518$$
$$x_{12} = 75904.5031947823$$
$$x_{13} = 80636.8914127834$$
$$x_{14} = 111397.611698726$$
$$x_{15} = 99566.5346489819$$
$$x_{16} = -77904.4008662005$$
$$x_{17} = 94834.1129910077$$
$$x_{18} = -101566.449604102$$
$$x_{19} = 61707.4260257409$$
$$x_{20} = -92101.6074405722$$
$$x_{21} = 101932.747623541$$
$$x_{22} = 109031.394011951$$
$$x_{23} = 33314.2246847333$$
$$x_{24} = -49510.4062468157$$
$$x_{25} = 118496.270498335$$
$$x_{26} = -56608.8197830767$$
$$x_{27} = 116130.05000039$$
$$x_{28} = -30582.0102415896$$
$$x_{29} = -32947.9631455023$$
$$x_{30} = -82636.7937706248$$
$$x_{31} = 90101.6978058649$$
$$x_{32} = 35680.2215432929$$
$$x_{33} = 59341.2638346033$$
$$x_{34} = 64073.5940850034$$
$$x_{35} = 47510.5715898323$$
$$x_{36} = 83003.0895866811$$
$$x_{37} = 78270.6958668897$$
$$x_{38} = -111031.312974353$$
$$x_{39} = 38046.2488519593$$
$$x_{40} = -68439.6525512153$$
$$x_{41} = -58974.9742863202$$
$$x_{42} = -89735.4009996172$$
$$x_{43} = 73538.3136738788$$
$$x_{44} = -96834.0254828412$$
$$x_{45} = 42778.3746065434$$
$$x_{46} = 30948.265261576$$
$$x_{47} = -113397.53150818$$
$$x_{48} = -99200.2368379737$$
$$x_{49} = -85002.9939963141$$
$$x_{50} = -94467.8156447326$$
$$x_{51} = 71172.1276184902$$
$$x_{52} = -73172.0196514105$$
$$x_{53} = 28582.3525725723$$
$$x_{54} = -87369.1964651273$$
$$x_{55} = 106665.177387825$$
$$x_{56} = 68805.9453861661$$
$$x_{57} = -118129.971352523$$
$$x_{58} = -70805.8341601038$$
$$x_{59} = -61341.1355120264$$
$$x_{60} = -106298.878992437$$
$$x_{61} = 104298.961898674$$
$$x_{62} = -28216.1057687048$$
$$x_{63} = 40412.3012615648$$
$$x_{64} = -66073.4752418611$$
$$x_{65} = 49876.6904558884$$
$$x_{66} = 87735.4929679377$$
$$x_{67} = 66439.7673853935$$
$$x_{68} = -80270.5959864298$$
$$x_{69} = 92467.9045272165$$
$$x_{70} = 85369.2901700512$$
$$x_{71} = 52242.8204439142$$
$$x_{72} = -40046.0265910906$$
$$x_{73} = -42412.0969465425$$
$$x_{74} = -103932.663684853$$
$$x_{75} = -37679.9777488965$$
$$x_{76} = -51876.5346235941$$
$$x_{77} = -47144.2892396889$$
$$x_{78} = 54608.9601080797$$
Signos de extremos en los puntos:
(-35313.95474466418, 1.67431803909311e-8*I)
(-108665.09544670767, 3.10186142467102e-9*I)
(97200.32306998238, 3.66653578425491e-9)
(-54242.67288207048, 8.79520300058616e-9*I)
(-44778.18540468717, 1.17262123680939e-8*I)
(-75538.20866028406, 5.3518935683966e-9*I)
(-63707.302711127995, 6.9099302505218e-9*I)
(113763.83038184051, 2.89568409921101e-9)
(45144.46559472521, 1.15837910753813e-8)
(-115763.75098648857, 2.82097089227423e-9*I)
(56975.10824275183, 8.17014477208121e-9)
(75904.50319478233, 5.31320016439687e-9)
(80636.89141278336, 4.8524025779054e-9)
(111397.61169872602, 2.98843401288235e-9)
(99566.53464898195, 3.53661188845978e-9)
(-77904.4008662005, 5.10992472669512e-9*I)
(94834.11299100767, 3.80461408032056e-9)
(-101566.4496041019, 3.43267022945952e-9*I)
(61707.42602574095, 7.24855341608485e-9)
(-92101.60744057223, 3.97517887323945e-9*I)
(101932.74762354096, 3.414183775632e-9)
(109031.39401195123, 3.08624318132831e-9)
(33314.22468473332, 1.82731291963931e-8)
(-49510.406246815655, 1.00858558258929e-8*I)
(118496.27049833543, 2.72395838197377e-9)
(-56608.81978307667, 8.24957052714269e-9*I)
(116130.0500003902, 2.80763450431894e-9)
(-30582.010241589636, 2.07758330340204e-8*I)
(-32947.96314550232, 1.85786705354849e-8*I)
(-82636.7937706248, 4.67732236218596e-9*I)
(90101.69780586493, 4.10826101848509e-9)
(35680.22154329286, 1.64860334647916e-8)
(59341.26383460335, 7.6863879970305e-9)
(64073.59408500344, 6.85076171709716e-9)
(47510.57158983226, 1.07293177585663e-8)
(83003.0895866811, 4.64639474194329e-9)
(78270.69586688966, 5.07409621607454e-9)
(-111031.3129743532, 3.0032347282563e-9*I)
(38046.24885195933, 1.49723414991928e-8)
(-68439.65255121535, 6.20577172651711e-9*I)
(-58974.974286320234, 7.75810852099888e-9*I)
(-89735.40099961721, 4.13344134045678e-9*I)
(73538.31367387876, 5.5716905836758e-9)
(-96834.02548284116, 3.68735975340016e-9*I)
(42778.374606543366, 1.25580171462192e-8)
(30948.265261575994, 2.04081211920561e-8)
(-113397.53150818005, 2.90972596473321e-9*I)
(-99200.23683797367, 3.55621841916662e-9*I)
(-85002.99399631414, 4.48338625810876e-9*I)
(-94467.81564473256, 3.82676400663795e-9*I)
(71172.12761849022, 5.85184167248094e-9)
(-73172.0196514105, 5.61358013982987e-9*I)
(28582.352572572272, 2.299378850275e-8)
(-87369.19646512732, 4.30249107663149e-9*I)
(106665.17738782511, 3.18950656677908e-9)
(68805.94538616607, 6.1562825058839e-9)
(-118129.97135252264, 2.73663793361535e-9*I)
(-70805.83416010381, 5.89730955969872e-9*I)
(-61341.13551202637, 7.31357591703849e-9*I)
(-106298.87899243688, 3.20600698123204e-9*I)
(104298.9618986742, 3.29865967786017e-9)
(-28216.105768704794, 2.34429293424775e-8*I)
(40412.30126156482, 1.36768825595649e-8)
(-66073.47524186112, 6.54209378630908e-9*I)
(49876.69045588843, 9.97495736294332e-9)
(87735.49296793774, 4.27557480886179e-9)
(66439.76738539347, 6.48806714390046e-9)
(-80270.59598642979, 4.88565458646478e-9*I)
(92467.9045272165, 3.95158171047675e-9)
(85369.29017005119, 4.45456176468658e-9)
(52242.82044391421, 9.30502550102191e-9)
(-40046.0265910906, 1.38649511390944e-8*I)
(-42412.09694654248, 1.27210474441791e-8*I)
(-103932.66368485343, 3.31611362979895e-9*I)
(-37679.97774889652, 1.51911808512933e-8*I)
(-51876.534623594074, 9.40374956168266e-9*I)
(-47144.28923968889, 1.08546006914101e-8*I)
(54608.96010807971, 8.70686139018676e-9)
Intervalos de crecimiento y decrecimiento de la función:Hallemos los intervalos donde la función crece y decrece y también los puntos mínimos y máximos de la función, para lo cual miramos cómo se comporta la función en los extremos con desviación mínima del extremo:
La función no tiene puntos mínimos
La función no tiene puntos máximos
No cambia el valor en todo el eje numérico