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$$2 \left(2 x + 1\right) \cos{\left(2 x \right)} - 2 \left(\log{\left(\cos{\left(2 x \right)} \right)} + 1\right) \sin{\left(2 x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -2.44680946626708$$
$$x_{2} = 18.0903511251597$$
$$x_{3} = -77.7639833644741$$
$$x_{4} = 96.6120274167753$$
$$x_{5} = -27.5092986332732$$
$$x_{6} = -40.0708949828962$$
$$x_{7} = 2.43177765419095$$
$$x_{8} = 74.6225935141479$$
$$x_{9} = 33.7893714796273$$
$$x_{10} = -33.7897333884118$$
$$x_{11} = -49.4934576869958$$
$$x_{12} = -5.55521248253785$$
$$x_{13} = 62.057642328025$$
$$x_{14} = -55.7755200623919$$
$$x_{15} = -46.3525201587164$$
$$x_{16} = 71.4813165948245$$
$$x_{17} = 30.6489779934667$$
$$x_{18} = 11.8151193655756$$
$$x_{19} = -62.0577758347618$$
$$x_{20} = 8.68026908528566$$
$$x_{21} = -68.3401773195391$$
$$x_{22} = -84.0466246713421$$
$$x_{23} = 68.3400636729733$$
$$x_{24} = 99.7534279538587$$
$$x_{25} = 36.9299300504498$$
$$x_{26} = 77.7638918737282$$
$$x_{27} = 80.9052094746002$$
$$x_{28} = -74.6226915752461$$
$$x_{29} = 24.3688897458978$$
$$x_{30} = -96.6120908021979$$
$$x_{31} = 46.3523038051329$$
$$x_{32} = 49.4932634530128$$
$$x_{33} = 55.775360640187$$
$$x_{34} = 84.0465444146651$$
$$x_{35} = -11.8169654654065$$
$$x_{36} = 90.3292599033518$$
$$x_{37} = 27.5087955578452$$
$$x_{38} = -93.4707047793721$$
$$x_{39} = -18.0913210332189$$
$$x_{40} = -90.3293309467508$$
$$x_{41} = -99.7534879843014$$
$$x_{42} = -24.3694992846271$$
$$x_{43} = -8.6831598094142$$
$$x_{44} = 40.0706204460855$$
$$x_{45} = 5.54983861038779$$
$$x_{46} = 58.9164816217787$$
$$x_{47} = 52.6342854482344$$
$$x_{48} = 14.9521207028286$$
$$x_{49} = -71.4814219980639$$
Signos de extremos en los puntos:
(-2.44680946626708, -3.95844741199041)
(18.090351125159692, -37.2317794549741)
(-77.76398336447409, -154.556247441498)
(96.61202741677526, -194.249250726336)
(-27.50929863327324, -54.0634256831093)
(-40.07089498289623, -79.1802694093777)
(2.4317776541909453, -5.93119398278953)
(74.6225935141479, -150.273862473449)
(33.78937147962734, -68.6195782823856)
(-33.78973338841183, -66.6207934183219)
(-49.49345768699583, -98.0219752815217)
(-5.5552124825378515, -10.1774751125309)
(62.05764232802505, -125.146609637475)
(-55.77552006239188, -110.584230055438)
(-46.35252015871643, -91.7411471403613)
(71.48131659482452, -143.991914831596)
(30.648977993466687, -62.3403910779368)
(11.815119365575594, -24.6877888630468)
(-62.05777583476179, -123.147116220775)
(8.680269085285664, -18.4221049294777)
(-68.34017731953911, -135.710489547029)
(-84.04662467134209, -167.120449740725)
(68.34006367297332, -137.710050233121)
(99.7534279538587, -200.531640507497)
(36.92993005044977, -74.8992492611467)
(77.76389187372821, -156.555884983063)
(80.90520947460024, -162.83797526324)
(-74.62269157524608, -148.274247945499)
(24.36888974589775, -49.783997720907)
(-96.6120908021979, -192.249512185622)
(46.35230380513288, -93.7403721422987)
(49.49326345301284, -100.021270329572)
(55.77536064018696, -112.583637606031)
(84.04654441466509, -169.12012711919)
(-11.816965465406525, -22.6927022041842)
(90.32925990335184, -181.684594464946)
(27.50879555784524, -56.0618083366753)
(-93.4707047793721, -185.967175797065)
(-18.091321033218914, -35.2346245578915)
(-90.32933094675076, -179.684883903404)
(-99.75348798430144, -198.531889583405)
(-24.36949928462711, -47.7859069101792)
(-8.683159809414196, -16.4292589664911)
(40.07062044608549, -81.1793145944256)
(5.549838610387786, -12.1655392407456)
(58.91648162177867, -118.865057668052)
(52.63428544823436, -106.302367791828)
(14.952120702828617, -30.95831189703)
(-71.48142199806385, -141.992325793145)
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:
Puntos mínimos de la función:
$$x_{1} = -2.44680946626708$$
$$x_{2} = 18.0903511251597$$
$$x_{3} = -77.7639833644741$$
$$x_{4} = 96.6120274167753$$
$$x_{5} = -27.5092986332732$$
$$x_{6} = -40.0708949828962$$
$$x_{7} = 2.43177765419095$$
$$x_{8} = 74.6225935141479$$
$$x_{9} = 33.7893714796273$$
$$x_{10} = -33.7897333884118$$
$$x_{11} = -49.4934576869958$$
$$x_{12} = -5.55521248253785$$
$$x_{13} = 62.057642328025$$
$$x_{14} = -55.7755200623919$$
$$x_{15} = -46.3525201587164$$
$$x_{16} = 71.4813165948245$$
$$x_{17} = 30.6489779934667$$
$$x_{18} = 11.8151193655756$$
$$x_{19} = -62.0577758347618$$
$$x_{20} = 8.68026908528566$$
$$x_{21} = -68.3401773195391$$
$$x_{22} = -84.0466246713421$$
$$x_{23} = 68.3400636729733$$
$$x_{24} = 99.7534279538587$$
$$x_{25} = 36.9299300504498$$
$$x_{26} = 77.7638918737282$$
$$x_{27} = 80.9052094746002$$
$$x_{28} = -74.6226915752461$$
$$x_{29} = 24.3688897458978$$
$$x_{30} = -96.6120908021979$$
$$x_{31} = 46.3523038051329$$
$$x_{32} = 49.4932634530128$$
$$x_{33} = 55.775360640187$$
$$x_{34} = 84.0465444146651$$
$$x_{35} = -11.8169654654065$$
$$x_{36} = 90.3292599033518$$
$$x_{37} = 27.5087955578452$$
$$x_{38} = -93.4707047793721$$
$$x_{39} = -18.0913210332189$$
$$x_{40} = -90.3293309467508$$
$$x_{41} = -99.7534879843014$$
$$x_{42} = -24.3694992846271$$
$$x_{43} = -8.6831598094142$$
$$x_{44} = 40.0706204460855$$
$$x_{45} = 5.54983861038779$$
$$x_{46} = 58.9164816217787$$
$$x_{47} = 52.6342854482344$$
$$x_{48} = 14.9521207028286$$
$$x_{49} = -71.4814219980639$$
La función no tiene puntos máximos
Decrece en los intervalos
$$\left[99.7534279538587, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -99.7534879843014\right]$$