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$$3 \frac{1}{2 x} \cos{\left(3 x \right)} - \frac{\sin{\left(3 x \right)}}{2 x^{2}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 88.4869374039331$$
$$x_{2} = -65.448149267704$$
$$x_{3} = -6.79043431976252$$
$$x_{4} = 170.168949124421$$
$$x_{5} = -49.7396498613733$$
$$x_{6} = -16.2247147439848$$
$$x_{7} = -29.8414069768057$$
$$x_{8} = 49.7396498613733$$
$$x_{9} = 66.4953735549544$$
$$x_{10} = 51.8341352242202$$
$$x_{11} = 56.0230857030463$$
$$x_{12} = 36.1252398838916$$
$$x_{13} = -50.7868934733971$$
$$x_{14} = -23.5572285705398$$
$$x_{15} = -1.49780315263635$$
$$x_{16} = 75.9203589492161$$
$$x_{17} = 80.1092256793491$$
$$x_{18} = 34.0306554883025$$
$$x_{19} = -100.006255101775$$
$$x_{20} = 62.3064710135101$$
$$x_{21} = 26.6993762096484$$
$$x_{22} = -53.9286135759886$$
$$x_{23} = -82.2036561197804$$
$$x_{24} = -71.7314832814509$$
$$x_{25} = -80.1092256793491$$
$$x_{26} = -62.3064710135101$$
$$x_{27} = -56.0230857030463$$
$$x_{28} = 82.2036561197804$$
$$x_{29} = -84.2980848042281$$
$$x_{30} = 93.722995310418$$
$$x_{31} = -34.0306554883025$$
$$x_{32} = 86.3925118604052$$
$$x_{33} = 5.74025175731026$$
$$x_{34} = -9.93719959696432$$
$$x_{35} = -7.839817499563$$
$$x_{36} = 58.1175522783976$$
$$x_{37} = -75.9203589492161$$
$$x_{38} = -67.5425970131389$$
$$x_{39} = 91.6285731099136$$
$$x_{40} = -27.7467308235745$$
$$x_{41} = 73.8259223276238$$
$$x_{42} = 27.7467308235745$$
$$x_{43} = -51.8341352242202$$
$$x_{44} = -3.63470721980963$$
$$x_{45} = 60.212013881401$$
$$x_{46} = 29.8414069768057$$
$$x_{47} = -73.8259223276238$$
$$x_{48} = -45.5506542337597$$
$$x_{49} = 95.8174163262761$$
$$x_{50} = 16.2247147439848$$
$$x_{51} = 38.2198035316744$$
$$x_{52} = 45.5506542337597$$
$$x_{53} = -38.2198035316744$$
$$x_{54} = 2.5750839456459$$
$$x_{55} = -25.6520087701104$$
$$x_{56} = -93.722995310418$$
$$x_{57} = 12.0335407481252$$
$$x_{58} = -14.1293045227106$$
$$x_{59} = -5.74025175731026$$
$$x_{60} = -43.4561415684628$$
$$x_{61} = 7.839817499563$$
$$x_{62} = -69.6370415919254$$
$$x_{63} = 214.151380376346$$
$$x_{64} = -91.6285731099136$$
$$x_{65} = 71.7314832814509$$
$$x_{66} = 100.006255101775$$
$$x_{67} = -89.534149641627$$
$$x_{68} = -58.1175522783976$$
$$x_{69} = 53.9286135759886$$
$$x_{70} = -78.014793341506$$
$$x_{71} = 84.2980848042281$$
$$x_{72} = 40.3143496657172$$
$$x_{73} = 37.1725240820437$$
$$x_{74} = -153.413716993446$$
$$x_{75} = -60.212013881401$$
$$x_{76} = -21.4623731968525$$
$$x_{77} = 78.014793341506$$
$$x_{78} = 14.1293045227106$$
$$x_{79} = -36.1252398838916$$
$$x_{80} = 20.4149100867915$$
$$x_{81} = -12.0335407481252$$
$$x_{82} = -31.9360462622872$$
$$x_{83} = 18.3198927626296$$
$$x_{84} = 31.9360462622872$$
$$x_{85} = -95.8174163262761$$
$$x_{86} = 97.9118362335106$$
$$x_{87} = 44.5033992843595$$
$$x_{88} = -47.6451565627964$$
$$x_{89} = 42.4088808811114$$
$$x_{90} = -351.334462172035$$
$$x_{91} = -97.9118362335106$$
$$x_{92} = 69.6370415919254$$
$$x_{93} = 9.93719959696432$$
$$x_{94} = 64.4009241109425$$
$$x_{95} = 22.5098115923814$$
Signos de extremos en los puntos:
(88.4869374039331, 0.00565051144349552)
(-65.448149267704, 0.00763953634790889)
(-6.790434319762521, 0.0735444360211112)
(170.1689491244206, 0.00293825074030404)
(-49.73964986137327, -0.0100521168532409)
(-16.224714743984794, -0.0308106810626306)
(-29.84140697680573, 0.0167541969512603)
(49.73964986137327, -0.0100521168532409)
(66.49537355495444, -0.00751922564151797)
(51.83413522422022, -0.00964595356826895)
(56.02308570304626, -0.00892473421535613)
(36.12523988389156, 0.0138401493761729)
(-50.786893473397086, 0.00984484768974962)
(-23.557228570539834, 0.0212227830972996)
(-1.4978031526363547, -0.325850442316833)
(75.9203589492161, 0.00658578525869541)
(80.10922567934914, 0.00624142434739368)
(34.03065548830255, 0.0146919302201117)
(-100.00625510177518, -0.00499965949213873)
(62.306471013510084, -0.00802473381440714)
(26.69937620964837, -0.0187255699826685)
(-53.92861357598856, -0.00927133882917417)
(-82.20365611978043, 0.00608240451771827)
(-71.73148328145086, 0.00697036473602969)
(-80.10922567934914, 0.00624142434739368)
(-62.306471013510084, -0.00802473381440714)
(-56.02308570304626, -0.00892473421535613)
(82.20365611978043, 0.00608240451771827)
(-84.29808480422805, 0.00593128648461355)
(93.72299531041797, -0.00533483630200461)
(-34.03065548830255, 0.0146919302201117)
(86.39251186040515, 0.00578749555419506)
(5.740251757310256, -0.0869577035192308)
(-9.93719959696432, -0.0502877025320981)
(-7.839817499563003, -0.063719425466419)
(58.11755227839756, -0.00860311139416558)
(-75.9203589492161, 0.00658578525869541)
(-67.54259701313894, 0.00740264563812724)
(91.62857310991362, -0.00545677701319961)
(-27.746730823574467, 0.0180188407230791)
(73.82592232762377, 0.00677261980241303)
(27.746730823574467, 0.0180188407230791)
(-51.83413522422022, -0.00964595356826895)
(-3.6347072198096333, -0.136987804234587)
(60.212013881400964, -0.00830386340098503)
(29.84140697680573, 0.0167541969512603)
(-73.82592232762377, 0.00677261980241303)
(-45.55065423375966, -0.010976496851203)
(95.81741632627612, -0.00521822643124976)
(16.224714743984794, -0.0308106810626306)
(38.21980353167436, 0.0130817256715564)
(45.55065423375966, -0.010976496851203)
(-38.21980353167436, 0.0130817256715564)
(2.5750839456459023, 0.192561830288849)
(-25.652008770110395, 0.0194900054805641)
(-93.72299531041797, -0.00533483630200461)
(12.033540748125203, -0.0415345984517238)
(-14.12930452271064, -0.0353776023435246)
(-5.740251757310256, -0.0869577035192308)
(-43.456141568462805, -0.0115055150594557)
(7.839817499563003, -0.063719425466419)
(-69.63704159192544, 0.00718000449883474)
(214.15138037634594, 0.00233479416954943)
(-91.62857310991362, -0.00545677701319961)
(71.73148328145086, 0.00697036473602969)
(100.00625510177518, -0.00499965949213873)
(-89.53414964162702, -0.00558442266892595)
(-58.11755227839756, -0.00860311139416558)
(53.92861357598856, -0.00927133882917417)
(-78.01479334150599, 0.00640898238229569)
(84.29808480422805, 0.00593128648461355)
(40.31434966571717, 0.0124021077755364)
(37.17252408204367, -0.0134502542107399)
(-153.41371699344606, 0.00325915328541868)
(-60.212013881400964, -0.00830386340098503)
(-21.46237319685247, 0.023293775711192)
(78.01479334150599, 0.00640898238229569)
(14.12930452271064, -0.0353776023435246)
(-36.12523988389156, 0.0138401493761729)
(20.414910086791465, -0.0244886389814967)
(-12.033540748125203, -0.0415345984517238)
(-31.93604626228723, 0.0156554372018487)
(18.319892762629646, -0.0272882194827047)
(31.93604626228723, 0.0156554372018487)
(-95.81741632627612, -0.00521822643124976)
(97.91183623351056, -0.00510660530671998)
(44.50339928435946, 0.0112347816877682)
(-47.64515656279642, -0.010493989314784)
(42.40888088111144, 0.0117896191899248)
(-351.3344621720351, -0.00142314469201501)
(-97.91183623351056, -0.00510660530671998)
(69.63704159192544, 0.00718000449883474)
(9.93719959696432, -0.0502877025320981)
(64.40092411094253, -0.00776375975233391)
(22.50981159238137, -0.0222101009198238)
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:
$$x_{1} = -49.7396498613733$$
$$x_{2} = -16.2247147439848$$
$$x_{3} = 49.7396498613733$$
$$x_{4} = 66.4953735549544$$
$$x_{5} = 51.8341352242202$$
$$x_{6} = 56.0230857030463$$
$$x_{7} = -1.49780315263635$$
$$x_{8} = -100.006255101775$$
$$x_{9} = 62.3064710135101$$
$$x_{10} = 26.6993762096484$$
$$x_{11} = -53.9286135759886$$
$$x_{12} = -62.3064710135101$$
$$x_{13} = -56.0230857030463$$
$$x_{14} = 93.722995310418$$
$$x_{15} = 5.74025175731026$$
$$x_{16} = -9.93719959696432$$
$$x_{17} = -7.839817499563$$
$$x_{18} = 58.1175522783976$$
$$x_{19} = 91.6285731099136$$
$$x_{20} = -51.8341352242202$$
$$x_{21} = -3.63470721980963$$
$$x_{22} = 60.212013881401$$
$$x_{23} = -45.5506542337597$$
$$x_{24} = 95.8174163262761$$
$$x_{25} = 16.2247147439848$$
$$x_{26} = 45.5506542337597$$
$$x_{27} = -93.722995310418$$
$$x_{28} = 12.0335407481252$$
$$x_{29} = -14.1293045227106$$
$$x_{30} = -5.74025175731026$$
$$x_{31} = -43.4561415684628$$
$$x_{32} = 7.839817499563$$
$$x_{33} = -91.6285731099136$$
$$x_{34} = 100.006255101775$$
$$x_{35} = -89.534149641627$$
$$x_{36} = -58.1175522783976$$
$$x_{37} = 53.9286135759886$$
$$x_{38} = 37.1725240820437$$
$$x_{39} = -60.212013881401$$
$$x_{40} = 14.1293045227106$$
$$x_{41} = 20.4149100867915$$
$$x_{42} = -12.0335407481252$$
$$x_{43} = 18.3198927626296$$
$$x_{44} = -95.8174163262761$$
$$x_{45} = 97.9118362335106$$
$$x_{46} = -47.6451565627964$$
$$x_{47} = -351.334462172035$$
$$x_{48} = -97.9118362335106$$
$$x_{49} = 9.93719959696432$$
$$x_{50} = 64.4009241109425$$
$$x_{51} = 22.5098115923814$$
Puntos máximos de la función:
$$x_{51} = 88.4869374039331$$
$$x_{51} = -65.448149267704$$
$$x_{51} = -6.79043431976252$$
$$x_{51} = 170.168949124421$$
$$x_{51} = -29.8414069768057$$
$$x_{51} = 36.1252398838916$$
$$x_{51} = -50.7868934733971$$
$$x_{51} = -23.5572285705398$$
$$x_{51} = 75.9203589492161$$
$$x_{51} = 80.1092256793491$$
$$x_{51} = 34.0306554883025$$
$$x_{51} = -82.2036561197804$$
$$x_{51} = -71.7314832814509$$
$$x_{51} = -80.1092256793491$$
$$x_{51} = 82.2036561197804$$
$$x_{51} = -84.2980848042281$$
$$x_{51} = -34.0306554883025$$
$$x_{51} = 86.3925118604052$$
$$x_{51} = -75.9203589492161$$
$$x_{51} = -67.5425970131389$$
$$x_{51} = -27.7467308235745$$
$$x_{51} = 73.8259223276238$$
$$x_{51} = 27.7467308235745$$
$$x_{51} = 29.8414069768057$$
$$x_{51} = -73.8259223276238$$
$$x_{51} = 38.2198035316744$$
$$x_{51} = -38.2198035316744$$
$$x_{51} = 2.5750839456459$$
$$x_{51} = -25.6520087701104$$
$$x_{51} = -69.6370415919254$$
$$x_{51} = 214.151380376346$$
$$x_{51} = 71.7314832814509$$
$$x_{51} = -78.014793341506$$
$$x_{51} = 84.2980848042281$$
$$x_{51} = 40.3143496657172$$
$$x_{51} = -153.413716993446$$
$$x_{51} = -21.4623731968525$$
$$x_{51} = 78.014793341506$$
$$x_{51} = -36.1252398838916$$
$$x_{51} = -31.9360462622872$$
$$x_{51} = 31.9360462622872$$
$$x_{51} = 44.5033992843595$$
$$x_{51} = 42.4088808811114$$
$$x_{51} = 69.6370415919254$$
Decrece en los intervalos
$$\left[100.006255101775, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -351.334462172035\right]$$