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$$\frac{\left(- 2 x - 1\right) \sin{\left(x \right)}}{\left(x^{2} + x\right)^{2}} + \frac{\cos{\left(x \right)}}{x^{2} + x} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -45.5086813437597$$
$$x_{2} = -4.21030687099956$$
$$x_{3} = 26.6299264227573$$
$$x_{4} = 92.6555164857957$$
$$x_{5} = 83.2283222304467$$
$$x_{6} = 39.219589713028$$
$$x_{7} = 32.9269488002951$$
$$x_{8} = 70.6577341444619$$
$$x_{9} = -54.9411479381075$$
$$x_{10} = 86.3707785763499$$
$$x_{11} = -7.57725556612152$$
$$x_{12} = 117.792818621253$$
$$x_{13} = -10.8034064905843$$
$$x_{14} = 67.5148435894255$$
$$x_{15} = 95.797809455818$$
$$x_{16} = 7.61134921493137$$
$$x_{17} = -86.3705105117496$$
$$x_{18} = -29.7769031039576$$
$$x_{19} = 20.3245505305776$$
$$x_{20} = -20.3197194675214$$
$$x_{21} = -80.0854867532991$$
$$x_{22} = 48.6540159233106$$
$$x_{23} = -36.0721397966768$$
$$x_{24} = -32.9251056906799$$
$$x_{25} = 64.3718273069464$$
$$x_{26} = 76.9431992968741$$
$$x_{27} = 17.1659377579221$$
$$x_{28} = -95.7975915481518$$
$$x_{29} = 36.0736755951908$$
$$x_{30} = -17.1591707365239$$
$$x_{31} = -1110.55120132688$$
$$x_{32} = -67.5144049183161$$
$$x_{33} = -39.2182902732601$$
$$x_{34} = -51.7973064208209$$
$$x_{35} = 58.0853366248753$$
$$x_{36} = 10.8203712765393$$
$$x_{37} = -73.8001477840841$$
$$x_{38} = -13.989779179916$$
$$x_{39} = -23.4750719861659$$
$$x_{40} = 13.9999390615957$$
$$x_{41} = 42.3648700479129$$
$$x_{42} = -42.3637562976215$$
$$x_{43} = 98.9400581721213$$
$$x_{44} = -64.3713447630826$$
$$x_{45} = 51.7980515774978$$
$$x_{46} = -58.0847440097565$$
$$x_{47} = -48.653171390021$$
$$x_{48} = -26.6271098269614$$
$$x_{49} = 23.478694106118$$
$$x_{50} = 61.2286660937368$$
$$x_{51} = -218.331508225881$$
$$x_{52} = 80.0857985366819$$
$$x_{53} = -61.2281327485587$$
$$x_{54} = -274.882068187917$$
$$x_{55} = 54.9418102849687$$
$$x_{56} = 4.31483662620088$$
$$x_{57} = 73.8005149257302$$
$$x_{58} = -70.6573336227392$$
$$x_{59} = -76.9428615292039$$
$$x_{60} = -89.5129250514858$$
$$x_{61} = -98.9398538844255$$
$$x_{62} = 45.5096465557431$$
$$x_{63} = 152.354159938248$$
$$x_{64} = 29.7791560404789$$
$$x_{65} = 89.5131746276428$$
$$x_{66} = -117.792674488859$$
$$x_{67} = -92.6552835490818$$
$$x_{68} = -83.2280335439062$$
Signos de extremos en los puntos:
(-45.50868134375969, -0.000493210791560672)
(-4.210306870999558, 0.0648533581866726)
(26.62992642275734, 0.00135541599741951)
(92.65551648579569, -0.000115211354183637)
(83.22832223044672, 0.000142608968015911)
(39.21958971302798, 0.000633153891451214)
(32.9269488002951, 0.000893567556392469)
(70.65773414446191, 0.000197426629471884)
(-54.94114793810752, 0.000337201247107331)
(86.3707785763499, -0.000132480477510489)
(-7.57725556612152, -0.0193018141186247)
(117.79281862125308, -7.14543928505629e-5)
(-10.803406490584345, 0.00926815978495185)
(67.51484358942552, -0.000216086861978215)
(95.79780945581795, 0.000107816502998618)
(7.611349214931373, 0.0148100372758499)
(-86.37051051174957, 0.000135584131658075)
(-29.77690310395756, 0.0011642998076989)
(20.32455053057763, 0.00229669400663664)
(-20.319719467521367, -0.00253442074006521)
(-80.08548675329911, 0.000157838260692457)
(48.654015923310595, -0.000413587736713029)
(-36.07213979667678, 0.000789187533574841)
(-32.92510569067994, -0.000949544928695192)
(64.3718273069464, 0.000237523844973448)
(76.94319929687411, 0.000166688923324479)
(17.165937757922052, -0.00318643265659244)
(-95.79759154815176, -0.000110091167941496)
(36.073675595190814, -0.000746612640870773)
(-17.15917073652391, 0.00358073081666456)
(-1110.5512013268826, 8.11546409922528e-7)
(-67.51440491831613, 0.000222584286098187)
(-39.2182902732601, -0.000666286882142444)
(-51.79730642082091, -0.000379771389388018)
(58.0853366248753, 0.000291206334797043)
(10.820371276539255, -0.00769886605705645)
(-73.80014778408407, 0.000186058232912999)
(-13.989779179916034, -0.00544318470484132)
(-23.47507198616592, 0.00188821359913657)
(13.999939061595747, 0.00471717789310325)
(42.36487004791293, -0.000543730543381711)
(-42.363756297621535, 0.000570020381249577)
(98.94005817212127, -0.000101111467629888)
(-64.3713447630826, -0.000245020070327294)
(51.79805157749776, 0.000365385477105757)
(-58.084744009756506, -0.000301408879392996)
(-48.653171390021036, 0.000430945828935977)
(-26.6271098269614, -0.00146119004117301)
(23.478694106118, -0.00173392813728352)
(61.22866609373683, -0.000262317249117401)
(-218.331508225881, 2.10737870238563e-5)
(80.08579853668186, -0.000153945135953131)
(-61.228132748558664, 0.000271027998585765)
(-274.8820681879171, 1.3282458096703e-5)
(54.94181028496868, -0.000325145747236153)
(4.314836626200884, -0.0402051800541067)
(73.8005149257302, -0.00018108343588889)
(-70.6573336227392, -0.00020309512269768)
(-76.9428615292039, -0.000171078764562527)
(-89.51292505148578, -0.000126182159056221)
(-98.9398538844255, 0.000103176232037189)
(45.50964655574305, 0.000472001603964367)
(152.35415993824822, 4.27969627227201e-5)
(29.779156040478902, -0.00108864195536588)
(89.51317462764281, 0.000123394005098754)
(-117.79267448885864, 7.26780029626325e-5)
(-92.65528354908184, 0.000117725365451097)
(-83.22803354390616, -0.000146077583560614)
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:
$$x_{1} = -45.5086813437597$$
$$x_{2} = 92.6555164857957$$
$$x_{3} = 86.3707785763499$$
$$x_{4} = -7.57725556612152$$
$$x_{5} = 117.792818621253$$
$$x_{6} = 67.5148435894255$$
$$x_{7} = -20.3197194675214$$
$$x_{8} = 48.6540159233106$$
$$x_{9} = -32.9251056906799$$
$$x_{10} = 17.1659377579221$$
$$x_{11} = -95.7975915481518$$
$$x_{12} = 36.0736755951908$$
$$x_{13} = -39.2182902732601$$
$$x_{14} = -51.7973064208209$$
$$x_{15} = 10.8203712765393$$
$$x_{16} = -13.989779179916$$
$$x_{17} = 42.3648700479129$$
$$x_{18} = 98.9400581721213$$
$$x_{19} = -64.3713447630826$$
$$x_{20} = -58.0847440097565$$
$$x_{21} = -26.6271098269614$$
$$x_{22} = 23.478694106118$$
$$x_{23} = 61.2286660937368$$
$$x_{24} = 80.0857985366819$$
$$x_{25} = 54.9418102849687$$
$$x_{26} = 4.31483662620088$$
$$x_{27} = 73.8005149257302$$
$$x_{28} = -70.6573336227392$$
$$x_{29} = -76.9428615292039$$
$$x_{30} = -89.5129250514858$$
$$x_{31} = 29.7791560404789$$
$$x_{32} = -83.2280335439062$$
Puntos máximos de la función:
$$x_{32} = -4.21030687099956$$
$$x_{32} = 26.6299264227573$$
$$x_{32} = 83.2283222304467$$
$$x_{32} = 39.219589713028$$
$$x_{32} = 32.9269488002951$$
$$x_{32} = 70.6577341444619$$
$$x_{32} = -54.9411479381075$$
$$x_{32} = -10.8034064905843$$
$$x_{32} = 95.797809455818$$
$$x_{32} = 7.61134921493137$$
$$x_{32} = -86.3705105117496$$
$$x_{32} = -29.7769031039576$$
$$x_{32} = 20.3245505305776$$
$$x_{32} = -80.0854867532991$$
$$x_{32} = -36.0721397966768$$
$$x_{32} = 64.3718273069464$$
$$x_{32} = 76.9431992968741$$
$$x_{32} = -17.1591707365239$$
$$x_{32} = -1110.55120132688$$
$$x_{32} = -67.5144049183161$$
$$x_{32} = 58.0853366248753$$
$$x_{32} = -73.8001477840841$$
$$x_{32} = -23.4750719861659$$
$$x_{32} = 13.9999390615957$$
$$x_{32} = -42.3637562976215$$
$$x_{32} = 51.7980515774978$$
$$x_{32} = -48.653171390021$$
$$x_{32} = -218.331508225881$$
$$x_{32} = -61.2281327485587$$
$$x_{32} = -274.882068187917$$
$$x_{32} = -98.9398538844255$$
$$x_{32} = 45.5096465557431$$
$$x_{32} = 152.354159938248$$
$$x_{32} = 89.5131746276428$$
$$x_{32} = -117.792674488859$$
$$x_{32} = -92.6552835490818$$
Decrece en los intervalos
$$\left[117.792818621253, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -95.7975915481518\right]$$