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$$x \cos{\left(x \right)} - \sin{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -45.5311340139913$$
$$x_{2} = 67.5294347771441$$
$$x_{3} = -14.0661939128315$$
$$x_{4} = 95.8081387868617$$
$$x_{5} = 4.49340945790906$$
$$x_{6} = 0$$
$$x_{7} = -58.1022547544956$$
$$x_{8} = 61.2447302603744$$
$$x_{9} = 29.811598790893$$
$$x_{10} = -23.519452498689$$
$$x_{11} = -48.6741442319544$$
$$x_{12} = -39.2444323611642$$
$$x_{13} = -89.5242209304172$$
$$x_{14} = 54.9596782878889$$
$$x_{15} = -76.9560263103312$$
$$x_{16} = 86.3822220347287$$
$$x_{17} = 14.0661939128315$$
$$x_{18} = -92.6661922776228$$
$$x_{19} = -98.9500628243319$$
$$x_{20} = -51.8169824872797$$
$$x_{21} = 45.5311340139913$$
$$x_{22} = -64.3871195905574$$
$$x_{23} = 23.519452498689$$
$$x_{24} = -42.3879135681319$$
$$x_{25} = 70.6716857116195$$
$$x_{26} = -0.000109308030426382$$
$$x_{27} = 58.1022547544956$$
$$x_{28} = 92.6661922776228$$
$$x_{29} = -95.8081387868617$$
$$x_{30} = -73.8138806006806$$
$$x_{31} = -67.5294347771441$$
$$x_{32} = -80.0981286289451$$
$$x_{33} = -54.9596782878889$$
$$x_{34} = 73.8138806006806$$
$$x_{35} = -10.9041216594289$$
$$x_{36} = -7.72525183693771$$
$$x_{37} = 42.3879135681319$$
$$x_{38} = 20.3713029592876$$
$$x_{39} = 32.9563890398225$$
$$x_{40} = 7.72525183693771$$
$$x_{41} = -70.6716857116195$$
$$x_{42} = 48.6741442319544$$
$$x_{43} = -32.9563890398225$$
$$x_{44} = 26.6660542588127$$
$$x_{45} = 64.3871195905574$$
$$x_{46} = 36.1006222443756$$
$$x_{47} = -17.2207552719308$$
$$x_{48} = -29.811598790893$$
$$x_{49} = 17.2207552719308$$
$$x_{50} = -20.3713029592876$$
$$x_{51} = 89.5242209304172$$
$$x_{52} = 98.9500628243319$$
$$x_{53} = -61.2447302603744$$
$$x_{54} = 51.8169824872797$$
$$x_{55} = 83.2401924707234$$
$$x_{56} = 39.2444323611642$$
$$x_{57} = -4.49340945790906$$
$$x_{58} = -86.3822220347287$$
$$x_{59} = -36.1006222443756$$
$$x_{60} = -83.2401924707234$$
$$x_{61} = -26.6660542588127$$
$$x_{62} = 80.0981286289451$$
$$x_{63} = 102.091966464908$$
$$x_{64} = 76.9560263103312$$
$$x_{65} = 10.9041216594289$$
Signos de extremos en los puntos:
(-45.53113401399128, 45.5640718849901)
(67.52943477714412, -67.5516452838858)
(-14.066193912831473, 14.1726087899197)
(95.8081387868617, 95.8237943661836)
(4.493409457909064, -4.82057247696292)
(0, 2)
(-58.10225475449559, 58.1280681227954)
(61.2447302603744, -61.2692194433423)
(29.81159879089296, -29.8618912060815)
(-23.519452498689006, -23.583181514714)
(-48.674144231954386, -48.7049559965241)
(-39.24443236116419, 39.2826440075821)
(-89.52422093041719, 89.5409753015629)
(54.959678287888934, -54.9869672600921)
(-76.95602631033118, 76.9755165900379)
(86.38222203472871, -86.3995857493168)
(14.066193912831473, 14.1726087899197)
(-92.66619227762284, -92.6823786254679)
(-98.95006282433188, -98.9652213409449)
(-51.81698248727967, 51.845926034626)
(45.53113401399128, 45.5640718849901)
(-64.38711959055742, 64.4104138344437)
(23.519452498689006, -23.583181514714)
(-42.38791356813192, -42.423292810847)
(70.6716857116195, 70.6929088487848)
(-0.00010930803042638249, 2)
(58.10225475449559, 58.1280681227954)
(92.66619227762284, -92.6823786254679)
(-95.8081387868617, 95.8237943661836)
(-73.81388060068065, -73.834200427952)
(-67.52943477714412, -67.5516452838858)
(-80.09812862894512, -80.1168544421343)
(-54.959678287888934, -54.9869672600921)
(73.81388060068065, -73.834200427952)
(-10.904121659428899, -11.0412050726493)
(-7.725251836937707, 7.91808032101862)
(42.38791356813192, -42.423292810847)
(20.37130295928756, 20.4448621458573)
(32.956389039822476, 33.0018862855255)
(7.725251836937707, 7.91808032101862)
(-70.6716857116195, 70.6929088487848)
(48.674144231954386, -48.7049559965241)
(-32.956389039822476, 33.0018862855255)
(26.666054258812675, 26.722272621796)
(64.38711959055742, 64.4104138344437)
(36.10062224437561, -36.1421594976335)
(-17.22075527193077, -17.3077373699048)
(-29.81159879089296, -29.8618912060815)
(17.22075527193077, -17.3077373699048)
(-20.37130295928756, 20.4448621458573)
(89.52422093041719, 89.5409753015629)
(98.95006282433188, -98.9652213409449)
(-61.2447302603744, -61.2692194433423)
(51.81698248727967, 51.845926034626)
(83.2401924707234, 83.2582115281411)
(39.24443236116419, 39.2826440075821)
(-4.493409457909064, -4.82057247696292)
(-86.38222203472871, -86.3995857493168)
(-36.10062224437561, -36.1421594976335)
(-83.2401924707234, 83.2582115281411)
(-26.666054258812675, 26.722272621796)
(80.09812862894512, -80.1168544421343)
(102.09196646490764, 102.106658512589)
(76.95602631033118, 76.9755165900379)
(10.904121659428899, -11.0412050726493)
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:
$$x_{1} = 67.5294347771441$$
$$x_{2} = 4.49340945790906$$
$$x_{3} = 61.2447302603744$$
$$x_{4} = 29.811598790893$$
$$x_{5} = -23.519452498689$$
$$x_{6} = -48.6741442319544$$
$$x_{7} = 54.9596782878889$$
$$x_{8} = 86.3822220347287$$
$$x_{9} = -92.6661922776228$$
$$x_{10} = -98.9500628243319$$
$$x_{11} = 23.519452498689$$
$$x_{12} = -42.3879135681319$$
$$x_{13} = 92.6661922776228$$
$$x_{14} = -73.8138806006806$$
$$x_{15} = -67.5294347771441$$
$$x_{16} = -80.0981286289451$$
$$x_{17} = -54.9596782878889$$
$$x_{18} = 73.8138806006806$$
$$x_{19} = -10.9041216594289$$
$$x_{20} = 42.3879135681319$$
$$x_{21} = 48.6741442319544$$
$$x_{22} = 36.1006222443756$$
$$x_{23} = -17.2207552719308$$
$$x_{24} = -29.811598790893$$
$$x_{25} = 17.2207552719308$$
$$x_{26} = 98.9500628243319$$
$$x_{27} = -61.2447302603744$$
$$x_{28} = -4.49340945790906$$
$$x_{29} = -86.3822220347287$$
$$x_{30} = -36.1006222443756$$
$$x_{31} = 80.0981286289451$$
$$x_{32} = 10.9041216594289$$
Puntos máximos de la función:
$$x_{32} = -45.5311340139913$$
$$x_{32} = -14.0661939128315$$
$$x_{32} = 95.8081387868617$$
$$x_{32} = -58.1022547544956$$
$$x_{32} = -39.2444323611642$$
$$x_{32} = -89.5242209304172$$
$$x_{32} = -76.9560263103312$$
$$x_{32} = 14.0661939128315$$
$$x_{32} = -51.8169824872797$$
$$x_{32} = 45.5311340139913$$
$$x_{32} = -64.3871195905574$$
$$x_{32} = 70.6716857116195$$
$$x_{32} = 58.1022547544956$$
$$x_{32} = -95.8081387868617$$
$$x_{32} = -7.72525183693771$$
$$x_{32} = 20.3713029592876$$
$$x_{32} = 32.9563890398225$$
$$x_{32} = 7.72525183693771$$
$$x_{32} = -70.6716857116195$$
$$x_{32} = -32.9563890398225$$
$$x_{32} = 26.6660542588127$$
$$x_{32} = 64.3871195905574$$
$$x_{32} = -20.3713029592876$$
$$x_{32} = 89.5242209304172$$
$$x_{32} = 51.8169824872797$$
$$x_{32} = 83.2401924707234$$
$$x_{32} = 39.2444323611642$$
$$x_{32} = -83.2401924707234$$
$$x_{32} = -26.6660542588127$$
$$x_{32} = 102.091966464908$$
$$x_{32} = 76.9560263103312$$
Decrece en los intervalos
$$\left[98.9500628243319, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -98.9500628243319\right]$$