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$$\frac{\left(- 2 x - 1\right) \sin{\left(2 x \right)}}{\left(x^{2} + x\right)^{2}} + \frac{2 \cos{\left(2 x \right)}}{x^{2} + x} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -8.57755878460975$$
$$x_{2} = 99.7405787929127$$
$$x_{3} = -18.0356521422536$$
$$x_{4} = 52.6122632039851$$
$$x_{5} = 3.81153864777937$$
$$x_{6} = 76.1771010903408$$
$$x_{7} = 84.0316886109242$$
$$x_{8} = -79.3188709297408$$
$$x_{9} = -5.3960161178562$$
$$x_{10} = 98.1697030564332$$
$$x_{11} = -41.6139419347968$$
$$x_{12} = -69.8932313533687$$
$$x_{13} = -90.3152218631357$$
$$x_{14} = -91.88611388134$$
$$x_{15} = -93.4570026652504$$
$$x_{16} = -47.8987395547818$$
$$x_{17} = -13.3127649854021$$
$$x_{18} = 44.7566476624499$$
$$x_{19} = 30.6144600567864$$
$$x_{20} = 38.4716808813945$$
$$x_{21} = -27.4703989990655$$
$$x_{22} = -60.4673209002417$$
$$x_{23} = 40.0429743654917$$
$$x_{24} = -68.3222681391823$$
$$x_{25} = 24.3272065905731$$
$$x_{26} = -58.8963002777715$$
$$x_{27} = 54.1833299748694$$
$$x_{28} = 33.7575267296448$$
$$x_{29} = -54.1831596359198$$
$$x_{30} = 19.610096072963$$
$$x_{31} = 2.171150616426$$
$$x_{32} = 10.1633207350938$$
$$x_{33} = -35.3285623057093$$
$$x_{34} = 55.754381638728$$
$$x_{35} = -49.4698742897642$$
$$x_{36} = -107.594879662083$$
$$x_{37} = 88.7443899294668$$
$$x_{38} = 85.6025928495405$$
$$x_{39} = -19.6087940910157$$
$$x_{40} = 82.4607802854273$$
$$x_{41} = -84.0316177976063$$
$$x_{42} = -24.3263609848619$$
$$x_{43} = -85.6025246115628$$
$$x_{44} = -32.1855459430969$$
$$x_{45} = 47.8989575337176$$
$$x_{46} = -40.0426624361667$$
$$x_{47} = 74.6061683782845$$
$$x_{48} = -33.7570877695276$$
$$x_{49} = -98.1696511719121$$
$$x_{50} = 22.7550493438209$$
$$x_{51} = -71.4641871782887$$
$$x_{52} = -182.995032277855$$
$$x_{53} = -2.04278694273841$$
$$x_{54} = -57.3252672523308$$
$$x_{55} = 25.8992016896926$$
$$x_{56} = -55.7542207657436$$
$$x_{57} = 32.1860288367118$$
$$x_{58} = -11.7365039593478$$
$$x_{59} = 16.4638956000575$$
$$x_{60} = 8.58439584086157$$
$$x_{61} = -76.1770149197568$$
$$x_{62} = 11.7401459632485$$
$$x_{63} = 46.3278146314103$$
$$x_{64} = -63.6093286419814$$
$$x_{65} = 96.5988247504869$$
$$x_{66} = -3.77551226807681$$
$$x_{67} = 77.7480283259493$$
$$x_{68} = 91.8861731050591$$
$$x_{69} = -153.149366393867$$
$$x_{70} = 594.545569420286$$
$$x_{71} = -99.7405285299269$$
$$x_{72} = -82.4607067481665$$
$$x_{73} = -113.878323707173$$
$$x_{74} = 63.609452231378$$
$$x_{75} = 68.3223752642964$$
$$x_{76} = -77.7479456026924$$
$$x_{77} = 62.0384599985962$$
$$x_{78} = -16.4620473680961$$
$$x_{79} = -25.8984556983654$$
$$x_{80} = -10.1584541766013$$
$$x_{81} = 60.4674576690199$$
$$x_{82} = 69.8933337165055$$
$$x_{83} = -38.4713429424298$$
$$x_{84} = 66.7514092373268$$
$$x_{85} = 90.315283165105$$
$$x_{86} = 18.0371914942542$$
$$x_{87} = -62.0383300698268$$
$$x_{88} = -46.3275816132535$$
$$x_{89} = 41.6142307464496$$
Signos de extremos en los puntos:
(-8.577558784609753, 0.0152678851401789)
(99.74057879291273, -9.9518097181322e-5)
(-18.03565214225364, 0.00324940028361327)
(52.61226320398511, -0.000354463806697022)
(3.8115386477793667, 0.0530803438895249)
(76.17710109034076, 0.000170078792168169)
(84.03168861092416, -0.000139941239636553)
(-79.31887092974084, -0.000160961534900173)
(-5.396016117856196, 0.0412865315478706)
(98.16970305643322, 0.000102712004677356)
(-41.613941934796834, -0.00059150379747292)
(-69.89323135336872, -0.000207655400847326)
(-90.31522186313566, 0.00012396144976026)
(-91.88611388134004, -0.000119736505781122)
(-93.45700266525037, 0.000115723940082336)
(-47.89873955478181, -0.000445059514441988)
(-13.312764985402064, -0.00608209811004663)
(44.756647662449865, 0.000488182527087483)
(30.614460056786445, -0.00103267419930574)
(38.47168088139449, 0.000658309683848812)
(-27.470398999065537, 0.0013742825139226)
(-60.46732090024165, -0.000278061278556521)
(40.04297436549173, -0.000608278881022657)
(-68.32226813918234, 0.000217386103359635)
(24.327206590573052, -0.0016216912568049)
(-58.89630027777149, 0.000293222637897845)
(54.18332997486937, 0.000334390388484724)
(33.7575267296448, -0.000851913468369442)
(-54.18315963591985, -0.000346965416191611)
(19.610096072963003, 0.00247117397756322)
(2.1711506164259973, -0.135408777690304)
(10.163320735093784, 0.00877528528585896)
(-35.32856230570934, -0.000824212900884144)
(55.75438163872798, -0.000315975188578022)
(-49.46987428976418, 0.000416962260254908)
(-107.59487966208341, -8.71872780346965e-5)
(88.7443899294668, 0.000125552255187314)
(85.60259284954046, 0.000134881657951662)
(-19.60879409101571, -0.00273675674670355)
(82.46078028542732, 0.000145290951740552)
(-84.03161779760633, 0.000143312032201463)
(-24.326360984861893, 0.00176073239267113)
(-85.60252461156277, -0.000138070253189809)
(-32.185545943096855, -0.000995793943918896)
(47.89895753371764, 0.000426856242680282)
(-40.04266243616672, 0.000639438459451703)
(74.60616837828448, -0.00017726767142935)
(-33.757087769527644, 0.000903927112952061)
(-98.16965117191212, -0.000104826079926504)
(22.755049343820914, 0.00184826717195533)
(-71.46418717828868, 0.000198563754138879)
(-182.99503227785502, -3.00258040504072e-5)
(-2.042786942738411, 0.380200445758368)
(-57.32526725233076, -0.000309658784052569)
(25.899201689692624, 0.00143437480688582)
(-55.7542207657436, 0.000327516754505827)
(32.186028836711785, 0.000935780665810573)
(-11.736503959347777, 0.0079045746326208)
(16.463895600057477, 0.00347193586069381)
(8.584395840861575, -0.0120807602018289)
(-76.17701491975676, -0.000174603544710541)
(11.740145963248548, -0.00666350491347488)
(46.32781463141033, -0.00045597676079871)
(-63.60932864198137, -0.000251064679842182)
(96.59882475048693, -0.000106062177105832)
(-3.775512268076811, -0.0910831373844674)
(77.74802832594926, -0.000163318529647479)
(91.88617310505911, 0.000117158370845637)
(-153.14936639386673, 4.29146256609059e-5)
(594.5455694202858, 2.82422466527796e-6)
(-99.74052852992688, 0.000101533846404738)
(-82.4607067481665, -0.00014885809207019)
(-113.87832370717318, -7.77913826205967e-5)
(63.60945223137802, 0.000243292909263776)
(68.32237526429635, -0.000211114354288824)
(-77.74794560269237, 0.000167574498725168)
(62.03845999859621, -0.000255668883580935)
(-16.46204736809609, -0.00392100037176162)
(-25.898455698365435, -0.00154959105457485)
(-10.158454176601259, -0.0106911008690572)
(60.46745766901991, 0.000269013837895944)
(69.89333371650548, 0.000201797147613106)
(-38.471342942429814, -0.000693446226265393)
(66.75140923732678, 0.000221092095511365)
(90.31528316510503, -0.000121246427979181)
(18.037191494254227, -0.00290801256731816)
(-62.03833006982679, 0.000264046197022343)
(-46.327581613253464, 0.000476095883528882)
(41.61423074644961, 0.000563742845718741)
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:
$$x_{1} = 99.7405787929127$$
$$x_{2} = 52.6122632039851$$
$$x_{3} = 84.0316886109242$$
$$x_{4} = -79.3188709297408$$
$$x_{5} = -41.6139419347968$$
$$x_{6} = -69.8932313533687$$
$$x_{7} = -91.88611388134$$
$$x_{8} = -47.8987395547818$$
$$x_{9} = -13.3127649854021$$
$$x_{10} = 30.6144600567864$$
$$x_{11} = -60.4673209002417$$
$$x_{12} = 40.0429743654917$$
$$x_{13} = 24.3272065905731$$
$$x_{14} = 33.7575267296448$$
$$x_{15} = -54.1831596359198$$
$$x_{16} = 2.171150616426$$
$$x_{17} = -35.3285623057093$$
$$x_{18} = 55.754381638728$$
$$x_{19} = -107.594879662083$$
$$x_{20} = -19.6087940910157$$
$$x_{21} = -85.6025246115628$$
$$x_{22} = -32.1855459430969$$
$$x_{23} = 74.6061683782845$$
$$x_{24} = -98.1696511719121$$
$$x_{25} = -182.995032277855$$
$$x_{26} = -57.3252672523308$$
$$x_{27} = 8.58439584086157$$
$$x_{28} = -76.1770149197568$$
$$x_{29} = 11.7401459632485$$
$$x_{30} = 46.3278146314103$$
$$x_{31} = -63.6093286419814$$
$$x_{32} = 96.5988247504869$$
$$x_{33} = -3.77551226807681$$
$$x_{34} = 77.7480283259493$$
$$x_{35} = -82.4607067481665$$
$$x_{36} = -113.878323707173$$
$$x_{37} = 68.3223752642964$$
$$x_{38} = 62.0384599985962$$
$$x_{39} = -16.4620473680961$$
$$x_{40} = -25.8984556983654$$
$$x_{41} = -10.1584541766013$$
$$x_{42} = -38.4713429424298$$
$$x_{43} = 90.315283165105$$
$$x_{44} = 18.0371914942542$$
Puntos máximos de la función:
$$x_{44} = -8.57755878460975$$
$$x_{44} = -18.0356521422536$$
$$x_{44} = 3.81153864777937$$
$$x_{44} = 76.1771010903408$$
$$x_{44} = -5.3960161178562$$
$$x_{44} = 98.1697030564332$$
$$x_{44} = -90.3152218631357$$
$$x_{44} = -93.4570026652504$$
$$x_{44} = 44.7566476624499$$
$$x_{44} = 38.4716808813945$$
$$x_{44} = -27.4703989990655$$
$$x_{44} = -68.3222681391823$$
$$x_{44} = -58.8963002777715$$
$$x_{44} = 54.1833299748694$$
$$x_{44} = 19.610096072963$$
$$x_{44} = 10.1633207350938$$
$$x_{44} = -49.4698742897642$$
$$x_{44} = 88.7443899294668$$
$$x_{44} = 85.6025928495405$$
$$x_{44} = 82.4607802854273$$
$$x_{44} = -84.0316177976063$$
$$x_{44} = -24.3263609848619$$
$$x_{44} = 47.8989575337176$$
$$x_{44} = -40.0426624361667$$
$$x_{44} = -33.7570877695276$$
$$x_{44} = 22.7550493438209$$
$$x_{44} = -71.4641871782887$$
$$x_{44} = -2.04278694273841$$
$$x_{44} = 25.8992016896926$$
$$x_{44} = -55.7542207657436$$
$$x_{44} = 32.1860288367118$$
$$x_{44} = -11.7365039593478$$
$$x_{44} = 16.4638956000575$$
$$x_{44} = 91.8861731050591$$
$$x_{44} = -153.149366393867$$
$$x_{44} = 594.545569420286$$
$$x_{44} = -99.7405285299269$$
$$x_{44} = 63.609452231378$$
$$x_{44} = -77.7479456026924$$
$$x_{44} = 60.4674576690199$$
$$x_{44} = 69.8933337165055$$
$$x_{44} = 66.7514092373268$$
$$x_{44} = -62.0383300698268$$
$$x_{44} = -46.3275816132535$$
$$x_{44} = 41.6142307464496$$
Decrece en los intervalos
$$\left[99.7405787929127, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -182.995032277855\right]$$