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$$\frac{- x \log{\left(x \right)} \sin{\left(x \right)} + \left(\log{\left(x \right)} + 1\right) \cos{\left(x \right)} + 4 \log{\left(x \right)}^{3} \cos{\left(x \right)} + \frac{12 \log{\left(x \right)}^{2} \sin{\left(x \right)}}{x}}{x} - \frac{x \log{\left(x \right)} \cos{\left(x \right)} + \log{\left(x \right)}^{3} \cdot 4 \sin{\left(x \right)}}{x^{2}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 98.0980232353048$$
$$x_{2} = 10.5800383047146$$
$$x_{3} = 85.5693349941896$$
$$x_{4} = 29.2747481834168$$
$$x_{5} = 23.0345943331873$$
$$x_{6} = 51.1451996487642$$
$$x_{7} = 76.1760639960431$$
$$x_{8} = 69.9156834689074$$
$$x_{9} = 16.8007379903746$$
$$x_{10} = 4.46329905906489$$
$$x_{11} = 35.5193565502737$$
$$x_{12} = 32.3965626626375$$
$$x_{13} = 88.7010738319037$$
$$x_{14} = 48.0186538423046$$
$$x_{15} = 63.6569381940139$$
$$x_{16} = 60.5282403072776$$
$$x_{17} = 94.9654316066838$$
$$x_{18} = 7.48684179215485$$
$$x_{19} = 101.230873284404$$
$$x_{20} = 1.93808241183695$$
$$x_{21} = 66.7860946501321$$
$$x_{22} = 54.2723378411623$$
$$x_{23} = 79.3068132003605$$
$$x_{24} = 44.8927438156265$$
$$x_{25} = 73.045680619917$$
$$x_{26} = 57.4000296769758$$
$$x_{27} = 19.9166798660777$$
$$x_{28} = 91.8331107420302$$
$$x_{29} = 38.6430344378889$$
$$x_{30} = 82.4379093647578$$
$$x_{31} = 41.7675186309165$$
$$x_{32} = 13.6877000191375$$
$$x_{33} = 26.1540358057069$$
Signos de extremos en los puntos:
(98.09802323530484, -6.0413034930559)
(10.580038304714588, -5.49286844750449)
(85.5693349941896, -6.06214692211206)
(29.27474818341678, -6.25128564470731)
(23.03459433318731, -6.21109699231111)
(51.145199648764226, 6.17884397939167)
(76.17606399604308, 6.08477422148628)
(69.9156834689074, 6.10365007516655)
(16.80073799037456, -6.04584203417928)
(4.463299059064888, -3.27604811153802)
(35.51935655027367, -6.2452461694519)
(32.396562662637486, 6.251628864618)
(88.70107383190371, 6.05600264147714)
(48.018653842304616, -6.19337996991761)
(63.65693819401388, 6.12573775229547)
(60.528240307277585, -6.13797878468673)
(94.96543160668377, 6.04561386568943)
(7.486841792154847, 4.79112952814098)
(101.23087328440374, 6.03753982806631)
(1.938082411836954, 0.320470110321477)
(66.78609465013214, -6.11428972186733)
(54.27233784116234, -6.16463753075327)
(79.30681320036045, -6.07650094621288)
(44.89274381562649, 6.2079202823438)
(73.04568061991704, -6.09381640877646)
(57.400029676975784, 6.15097158413846)
(19.916679866077732, 6.15307027696914)
(91.83311074203024, -6.05050269623293)
(38.64303443788892, 6.23478856294615)
(82.4379093647578, 6.06896881877626)
(41.76751863091648, -6.22197137975332)
(13.687700019137498, 5.85160013827065)
(26.154035805706908, 6.24003503563682)
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:
$$x_{1} = 98.0980232353048$$
$$x_{2} = 10.5800383047146$$
$$x_{3} = 85.5693349941896$$
$$x_{4} = 29.2747481834168$$
$$x_{5} = 23.0345943331873$$
$$x_{6} = 16.8007379903746$$
$$x_{7} = 4.46329905906489$$
$$x_{8} = 35.5193565502737$$
$$x_{9} = 48.0186538423046$$
$$x_{10} = 60.5282403072776$$
$$x_{11} = 66.7860946501321$$
$$x_{12} = 54.2723378411623$$
$$x_{13} = 79.3068132003605$$
$$x_{14} = 73.045680619917$$
$$x_{15} = 91.8331107420302$$
$$x_{16} = 41.7675186309165$$
Puntos máximos de la función:
$$x_{16} = 51.1451996487642$$
$$x_{16} = 76.1760639960431$$
$$x_{16} = 69.9156834689074$$
$$x_{16} = 32.3965626626375$$
$$x_{16} = 88.7010738319037$$
$$x_{16} = 63.6569381940139$$
$$x_{16} = 94.9654316066838$$
$$x_{16} = 7.48684179215485$$
$$x_{16} = 101.230873284404$$
$$x_{16} = 1.93808241183695$$
$$x_{16} = 44.8927438156265$$
$$x_{16} = 57.4000296769758$$
$$x_{16} = 19.9166798660777$$
$$x_{16} = 38.6430344378889$$
$$x_{16} = 82.4379093647578$$
$$x_{16} = 13.6877000191375$$
$$x_{16} = 26.1540358057069$$
Decrece en los intervalos
$$\left[98.0980232353048, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, 4.46329905906489\right]$$