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$$- x \sin{\left(x \right)} + x \cos{\left(x \right)} + \sin{\left(x \right)} + \cos{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -18.119291621421$$
$$x_{2} = 101.326231870557$$
$$x_{3} = -96.6143241603692$$
$$x_{4} = 76.1967450163399$$
$$x_{5} = 35.3711814271828$$
$$x_{6} = -27.525250026105$$
$$x_{7} = -62.0625662865258$$
$$x_{8} = 85.6200787826806$$
$$x_{9} = 4.1627493368126$$
$$x_{10} = 60.492188136142$$
$$x_{11} = -68.3442709758693$$
$$x_{12} = 44.7900180082647$$
$$x_{13} = 79.3378181652015$$
$$x_{14} = -71.485220862291$$
$$x_{15} = -40.0802511015808$$
$$x_{16} = -90.3318586299385$$
$$x_{17} = -52.6406713811732$$
$$x_{18} = -49.5002834509857$$
$$x_{19} = 51.0704589102849$$
$$x_{20} = -43.2200322784808$$
$$x_{21} = -8.75313144558265$$
$$x_{22} = 54.2109176513576$$
$$x_{23} = 38.5104711360153$$
$$x_{24} = 29.0940897621002$$
$$x_{25} = 16.5536975718234$$
$$x_{26} = -93.4730793036062$$
$$x_{27} = -5.67228968340682$$
$$x_{28} = -74.6262248358581$$
$$x_{29} = 47.9301486357051$$
$$x_{30} = 95.0436988589063$$
$$x_{31} = 13.4261132241755$$
$$x_{32} = 88.7612581637789$$
$$x_{33} = -46.3600585879736$$
$$x_{34} = -14.9891811736395$$
$$x_{35} = 73.0557165239248$$
$$x_{36} = -0.402628174188112$$
$$x_{37} = 69.9147387028857$$
$$x_{38} = 57.3515004967328$$
$$x_{39} = 7.20646720968486$$
$$x_{40} = -21.2527684271428$$
$$x_{41} = -80.9083698613449$$
$$x_{42} = -24.3883233381018$$
$$x_{43} = -36.940777426275$$
$$x_{44} = 91.9024657889622$$
$$x_{45} = 66.7738186988218$$
$$x_{46} = -87.1906647520128$$
$$x_{47} = 63.6329650666866$$
$$x_{48} = -2.70973013143952$$
$$x_{49} = 98.1849549323352$$
$$x_{50} = -11.8650548496173$$
$$x_{51} = 19.6857087307627$$
$$x_{52} = -58.9218322634797$$
$$x_{53} = 22.8203392800723$$
$$x_{54} = 32.2323394923898$$
$$x_{55} = 10.3068958192079$$
$$x_{56} = -84.0495006728084$$
$$x_{57} = 41.6501075899818$$
$$x_{58} = 1.40422360239197$$
$$x_{59} = 25.9566461271548$$
$$x_{60} = -65.2033829872561$$
$$x_{61} = -30.6631292754598$$
$$x_{62} = -77.7672763467182$$
$$x_{63} = -33.8016967133026$$
$$x_{64} = -55.781194869671$$
$$x_{65} = -99.7555909164973$$
$$x_{66} = 82.4789308711661$$
Signos de extremos en los puntos:
(-18.11929162142097, -25.585611797501)
(101.32623187055665, 143.289953328736)
(-96.61432416036915, 136.625969274402)
(76.19674501633988, 107.749191396434)
(35.371181427182776, -50.0024254251706)
(-27.52525002610497, 38.9009179107362)
(-62.06256628652584, -87.7583317255229)
(85.6200787826806, -121.076818814706)
(4.162749336812597, -5.72416665255235)
(60.492188136142026, -85.5371860502751)
(-68.34427097586932, -96.643050337486)
(44.790018008264745, 63.3268696747378)
(79.33781816520154, -112.191706913287)
(-71.485220862291, 101.085478654273)
(-40.08025110158081, 56.6644006494057)
(-90.33185862993847, 127.740712430106)
(-52.64067138117324, 74.4317223259786)
(-49.50028345098569, -69.9896916649642)
(51.070458910284906, 72.2106938973383)
(-43.22003227848084, -61.1060017544374)
(-8.753131445582648, 12.29879618724)
(54.21091765135759, -76.6527746759208)
(38.51047113601533, 54.4436784383038)
(29.094089762100186, -41.1209737013462)
(16.553697571823395, -23.3678642299102)
(-93.47307930360616, -132.183332299788)
(-5.672289683406819, -7.90000171525038)
(-74.62622483585812, -105.527945235211)
(47.93014863570506, -67.7687182016179)
(95.04369885890632, 134.404648754957)
(13.426113224175548, 18.9349430012167)
(88.76125816377889, 125.519409477002)
(-46.360058587973604, 65.5477764282124)
(-14.989181173639471, 21.1508857212333)
(73.05571652392481, -103.306707470089)
(-0.4026281741881116, -0.212666853440747)
(69.91473870288569, 98.8642593906476)
(57.35150049673278, 81.0949432845246)
(7.206467209684859, 10.0947571927551)
(-21.25276842714282, 30.0227372130842)
(-80.90836986134488, -114.412975368689)
(-24.388323338101774, -34.4613404755723)
(-36.94077742627499, -52.2230173223486)
(91.90246578896223, -129.962020117231)
(66.77381869882177, -94.4218522149538)
(-87.19066475201284, -123.298111513691)
(63.63296506668664, 89.9794919977029)
(-2.7097301314395232, 3.59513659164769)
(98.18495493233517, -138.847293663112)
(-11.865054849617264, -16.7204413691124)
(19.685708730762727, 27.803945837067)
(-58.92183226347968, 83.3160561385281)
(22.820339280072254, -32.2418920480374)
(32.23233949238981, 45.5614896762973)
(10.306895819207908, -14.5080272258939)
(-84.04950067280843, 118.855531675096)
(41.650107589981786, -58.8851770547231)
(1.4042236023919696, 1.61761265536487)
(25.956646127154848, 36.6810294350162)
(-65.2033829872561, 92.2006658125594)
(-30.66312927545978, -43.3411711748992)
(-77.76727634671825, 109.970445445222)
(-33.801696713302576, 47.7819123762193)
(-55.78119486967102, -78.873848928134)
(-99.75559091649727, -141.068621738359)
(82.47893087116606, 116.634250412371)
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:
$$x_{1} = -18.119291621421$$
$$x_{2} = 35.3711814271828$$
$$x_{3} = -62.0625662865258$$
$$x_{4} = 85.6200787826806$$
$$x_{5} = 4.1627493368126$$
$$x_{6} = 60.492188136142$$
$$x_{7} = -68.3442709758693$$
$$x_{8} = 79.3378181652015$$
$$x_{9} = -49.5002834509857$$
$$x_{10} = -43.2200322784808$$
$$x_{11} = 54.2109176513576$$
$$x_{12} = 29.0940897621002$$
$$x_{13} = 16.5536975718234$$
$$x_{14} = -93.4730793036062$$
$$x_{15} = -5.67228968340682$$
$$x_{16} = -74.6262248358581$$
$$x_{17} = 47.9301486357051$$
$$x_{18} = 73.0557165239248$$
$$x_{19} = -0.402628174188112$$
$$x_{20} = -80.9083698613449$$
$$x_{21} = -24.3883233381018$$
$$x_{22} = -36.940777426275$$
$$x_{23} = 91.9024657889622$$
$$x_{24} = 66.7738186988218$$
$$x_{25} = -87.1906647520128$$
$$x_{26} = 98.1849549323352$$
$$x_{27} = -11.8650548496173$$
$$x_{28} = 22.8203392800723$$
$$x_{29} = 10.3068958192079$$
$$x_{30} = 41.6501075899818$$
$$x_{31} = -30.6631292754598$$
$$x_{32} = -55.781194869671$$
$$x_{33} = -99.7555909164973$$
Puntos máximos de la función:
$$x_{33} = 101.326231870557$$
$$x_{33} = -96.6143241603692$$
$$x_{33} = 76.1967450163399$$
$$x_{33} = -27.525250026105$$
$$x_{33} = 44.7900180082647$$
$$x_{33} = -71.485220862291$$
$$x_{33} = -40.0802511015808$$
$$x_{33} = -90.3318586299385$$
$$x_{33} = -52.6406713811732$$
$$x_{33} = 51.0704589102849$$
$$x_{33} = -8.75313144558265$$
$$x_{33} = 38.5104711360153$$
$$x_{33} = 95.0436988589063$$
$$x_{33} = 13.4261132241755$$
$$x_{33} = 88.7612581637789$$
$$x_{33} = -46.3600585879736$$
$$x_{33} = -14.9891811736395$$
$$x_{33} = 69.9147387028857$$
$$x_{33} = 57.3515004967328$$
$$x_{33} = 7.20646720968486$$
$$x_{33} = -21.2527684271428$$
$$x_{33} = 63.6329650666866$$
$$x_{33} = -2.70973013143952$$
$$x_{33} = 19.6857087307627$$
$$x_{33} = -58.9218322634797$$
$$x_{33} = 32.2323394923898$$
$$x_{33} = -84.0495006728084$$
$$x_{33} = 1.40422360239197$$
$$x_{33} = 25.9566461271548$$
$$x_{33} = -65.2033829872561$$
$$x_{33} = -77.7672763467182$$
$$x_{33} = -33.8016967133026$$
$$x_{33} = 82.4789308711661$$
Decrece en los intervalos
$$\left[98.1849549323352, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -99.7555909164973\right]$$