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$$\frac{1}{5 x^{2}} \left(2 \cos{\left(2 x \right)} - 2 \tan^{2}{\left(2 x \right)} - 2\right) - \frac{2 \left(\sin{\left(2 x \right)} - \tan{\left(2 x \right)}\right)}{5 x^{3}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 21.9911485852498$$
$$x_{2} = -43.9822971741826$$
$$x_{3} = 50.2654824462671$$
$$x_{4} = -3.14159367206719$$
$$x_{5} = 9.42477975159723$$
$$x_{6} = -78.5398146072499$$
$$x_{7} = -28.2743335951363$$
$$x_{8} = 53.4070767599789$$
$$x_{9} = 94.2477891700323$$
$$x_{10} = 106.81415017447$$
$$x_{11} = 43.9822971696928$$
$$x_{12} = -21.9911520202976$$
$$x_{13} = -84.8229948780466$$
$$x_{14} = 18.8495544106941$$
$$x_{15} = -94.2477793653754$$
$$x_{16} = -6.28318497322744$$
$$x_{17} = -21.9911485863403$$
$$x_{18} = 87.9645974073283$$
$$x_{19} = 56.5486644203727$$
$$x_{20} = 31.4159266894911$$
$$x_{21} = -65.9734457641547$$
$$x_{22} = 12.56637033265$$
$$x_{23} = -12.5663684741962$$
$$x_{24} = 28.2743350876814$$
$$x_{25} = -47.1238856879453$$
$$x_{26} = -53.4070754119299$$
$$x_{27} = -75.3982240033605$$
$$x_{28} = -50.2654821876287$$
$$x_{29} = -307.876079610755$$
$$x_{30} = -31.4159268197537$$
$$x_{31} = 69.1150396388453$$
$$x_{32} = 84.8230003212481$$
$$x_{33} = 106.814158618644$$
$$x_{34} = 53.4070769996658$$
$$x_{35} = -69.1150391984341$$
$$x_{36} = -15.7079632968348$$
$$x_{37} = 6.28318528343352$$
$$x_{38} = 34.55751893149$$
$$x_{39} = 81.6814093501194$$
$$x_{40} = 78.5398161080548$$
$$x_{41} = -9.42477775579947$$
$$x_{42} = -5419.2475564769$$
$$x_{43} = 25.1327409932573$$
$$x_{44} = 40.8407030493862$$
$$x_{45} = 62.8318516813035$$
$$x_{46} = 15.7079635620265$$
$$x_{47} = 94.2477796093512$$
$$x_{48} = -87.9645958833628$$
$$x_{49} = 15.7079629499178$$
$$x_{50} = -62.8318546671231$$
$$x_{51} = -157.079633768493$$
$$x_{52} = 100.530964694397$$
$$x_{53} = -34.5575134191745$$
$$x_{54} = 694.292002804052$$
$$x_{55} = -59.6902610917673$$
$$x_{56} = -62.8318314321161$$
$$x_{57} = -37.6991118779023$$
$$x_{58} = 637.743271833965$$
$$x_{59} = -25.1327424771655$$
$$x_{60} = 84.8230007146657$$
$$x_{61} = 40.840704622168$$
$$x_{62} = -12.5663725649891$$
$$x_{63} = 59.6902568429577$$
$$x_{64} = -21.9911508993257$$
$$x_{65} = -72.2566307771538$$
$$x_{66} = -91.1061873886045$$
$$x_{67} = -100.530963291808$$
$$x_{68} = -65.9734415661813$$
$$x_{69} = 65.973445753531$$
$$x_{70} = -9.4247782164521$$
$$x_{71} = -34.5575172345899$$
$$x_{72} = 31.4159284594043$$
$$x_{73} = 25.1327471896073$$
$$x_{74} = -59.69026045883$$
$$x_{75} = -56.5486659223628$$
$$x_{76} = -47.1238908993332$$
$$x_{77} = -53.407075051379$$
$$x_{78} = 56.5486675207376$$
$$x_{79} = -128.8052915447$$
$$x_{80} = -97.3893725951708$$
$$x_{81} = 75.3982254648674$$
$$x_{82} = 37.6991121614444$$
$$x_{83} = 87.9645943369138$$
$$x_{84} = 97.3893738664298$$
$$x_{85} = -72.2566406956633$$
$$x_{86} = 25.1327454174505$$
$$x_{87} = 72.2566310277059$$
$$x_{88} = -116.238926728588$$
$$x_{89} = -25.1327411917929$$
$$x_{90} = -87.9645943572683$$
$$x_{91} = 59.6902607558459$$
$$x_{92} = -81.6814090397131$$
$$x_{93} = -6.2831859215273$$
$$x_{94} = 28.2743338649667$$
Signos de extremos en los puntos:
(21.991148585249814, -1.36834152935053e-27)
(-43.98229717418262, 5.47336611648547e-27)
(50.26548244626705, 2.61909121209733e-28)
(-3.141593672067188, 8.56335160387919e-20)
(9.424779751597232, -5.17260828328557e-20)
(-78.53981460724994, -6.74412895450212e-22)
(-28.274333595136337, -2.37071087580739e-23)
(53.407076759978914, -1.25752052350721e-21)
(94.24778917003226, -7.87480831859584e-20)
(106.8141501744696, 7.42408139068577e-27)
(43.9822971696928, -3.42085382350184e-27)
(-21.991152020297637, 6.76434278750329e-20)
(-84.82299487804659, -3.44836029256134e-20)
(18.8495544106941, 7.76525793868636e-21)
(-94.24777936537538, -1.2801838535142e-24)
(-6.283184973227436, -7.54700641383681e-22)
(-21.991148586340273, 2.73668305842966e-27)
(87.96459740732828, -3.10042086124602e-21)
(56.54866442037269, 9.35702456894141e-21)
(31.415926689491066, -2.93941651365359e-24)
(-65.97344576415469, 1.0946732232015e-26)
(12.566370332650013, 1.13312367230226e-22)
(-12.566368474196222, -4.96600647851674e-20)
(28.274335087681372, -1.75257762934892e-21)
(-47.123885687945275, -2.51190328063293e-20)
(-53.407075411929945, 7.63937965812649e-24)
(-75.39822400336053, 4.49226520719432e-24)
(-50.26548218762871, -6.21877023800059e-24)
(-307.87607961075526, -7.24048149128697e-25)
(-31.41592681975372, 1.85376339177803e-23)
(69.11503963884533, -3.34902323775326e-22)
(84.82300032124813, 2.59044681227424e-22)
(106.8141586186443, -4.15088639894871e-20)
(53.407076999665826, -1.88945827493749e-21)
(-69.11503919843409, 9.21526657934905e-23)
(-15.707963296834812, 8.04584817039571e-26)
(6.283185283433521, 2.68194942026754e-25)
(34.55751893148998, 1.15080012336316e-23)
(81.68140935011942, -5.44642027241136e-24)
(78.53981610805478, 1.61174432093063e-24)
(-9.424777755799473, -7.7478541592103e-23)
(-5419.247556476904, 3.27276488550325e-19)
(25.132740993257293, 1.65275134871563e-23)
(40.84070304938618, 1.45400389421248e-21)
(62.83185168130349, 5.44800497430811e-22)
(15.707963562026517, -8.24753048605364e-23)
(94.24777960935116, 0)
(-87.96459588336278, 4.1000984147644e-22)
(15.707962949917755, 1.04274196894208e-22)
(-62.83185466712309, 8.22779122946874e-22)
(-157.07963376849327, 4.1874455459254e-23)
(100.5309646943969, 8.47537919575533e-25)
(-34.55751341917453, -1.28707512830021e-19)
(694.2920028040515, -3.04002266536785e-20)
(-59.69026109176733, 6.86103560660808e-23)
(-62.83183143211614, -2.0534446835163e-18)
(-37.69911187790228, 2.42120431496739e-26)
(637.7432718339654, 9.83842279365981e-20)
(-25.132742477165483, 2.46444305881793e-21)
(84.82300071466572, 9.00899565853611e-23)
(40.840704622168005, -9.45823569570209e-25)
(-12.566372564989145, 3.75998461352168e-20)
(59.69025684295767, 1.0261267416246e-20)
(-21.991150899325685, 2.07690117635025e-20)
(-72.2566307771538, -2.55520322713383e-24)
(-91.10618738860452, 7.90616990374342e-24)
(-100.5309632918081, -3.38453644116207e-22)
(-65.97344156618126, -1.32245883404189e-20)
(65.97344575353104, -4.2570625360435e-27)
(-9.424778216452097, 1.50665949229438e-22)
(-34.55751723458987, -5.00465113583862e-21)
(31.415928459404327, -5.76863644144973e-21)
(25.132747189607272, -2.68251670080996e-19)
(-59.69026045883004, 1.48584454091146e-26)
(-56.5486659223628, -1.56419245716205e-21)
(-47.12389089933321, 4.73586946874928e-22)
(-53.40707505137898, -5.93926512052349e-26)
(56.54866752073763, 3.62890934290012e-24)
(-128.80529154470034, -1.83942552568121e-20)
(-97.38937259517078, 3.13908081626509e-24)
(75.39822546486742, -7.91920021578964e-22)
(37.69911216144444, -1.81627570187597e-23)
(87.96459433691378, -4.78919535317173e-27)
(97.38937386642984, -3.48826439494461e-22)
(-72.2566406956633, 1.38255827505777e-19)
(25.13274541745045, -9.30802412398127e-20)
(72.25663102770594, 6.3373095471561e-29)
(-116.23892672858797, -1.82088892263424e-22)
(-25.132741191792892, -6.70487351969117e-26)
(-87.96459435726828, 1.88146960216103e-26)
(59.69026075584593, -8.64167176393993e-24)
(-81.68140903971315, 1.19021422941574e-26)
(-6.2831859215273, 4.69877442993328e-21)
(28.27433386496669, 6.62209729206313e-27)
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
Decrece en todo el eje numérico