Para hallar los extremos hay que resolver la ecuación
$$\frac{d}{d z} f{\left(z \right)} = 0$$
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
$$\frac{d}{d z} f{\left(z \right)} = $$
primera derivada$$- \frac{2 z \sin{\left(z \right)}}{\left(z^{2} - 1\right)^{2}} + \frac{\cos{\left(z \right)}}{z^{2} - 1} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$z_{1} = -51.7976718062027$$
$$z_{2} = -58.0850352160434$$
$$z_{3} = -61.2283950657729$$
$$z_{4} = 73.8003288675086$$
$$z_{5} = -42.3643000278463$$
$$z_{6} = -36.0728864084812$$
$$z_{7} = 86.3706429922226$$
$$z_{8} = -83.2281761528687$$
$$z_{9} = 32.9259992567895$$
$$z_{10} = 80.0856406984281$$
$$z_{11} = -4.2502319840436$$
$$z_{12} = 29.7779917432681$$
$$z_{13} = 26.6284652377851$$
$$z_{14} = -73.8003288675086$$
$$z_{15} = -32.9259992567895$$
$$z_{16} = -98.9399549958912$$
$$z_{17} = 42.3643000278463$$
$$z_{18} = 20.3220161353369$$
$$z_{19} = -67.5146210051587$$
$$z_{20} = -64.3715822869017$$
$$z_{21} = -39.2189234266452$$
$$z_{22} = 67.5146210051587$$
$$z_{23} = 23.4768059032848$$
$$z_{24} = 64.3715822869017$$
$$z_{25} = -86.3706429922226$$
$$z_{26} = -70.6575310493539$$
$$z_{27} = -89.5130484454873$$
$$z_{28} = -26.6284652377851$$
$$z_{29} = -7.59205618191083$$
$$z_{30} = -95.7976993646524$$
$$z_{31} = 39.2189234266452$$
$$z_{32} = 89.5130484454873$$
$$z_{33} = -17.1623570970183$$
$$z_{34} = 76.9430282181184$$
$$z_{35} = 4.2502319840436$$
$$z_{36} = -212.048072363693$$
$$z_{37} = 10.8111042087213$$
$$z_{38} = -92.6553987604331$$
$$z_{39} = 17.1623570970183$$
$$z_{40} = 83.2281761528687$$
$$z_{41} = -45.5091533451563$$
$$z_{42} = 54.9414730837878$$
$$z_{43} = -76.9430282181184$$
$$z_{44} = 13.9944961126907$$
$$z_{45} = -54.9414730837878$$
$$z_{46} = -48.6535849776189$$
$$z_{47} = 45.5091533451563$$
$$z_{48} = -13.9944961126907$$
$$z_{49} = 70.6575310493539$$
$$z_{50} = 98.9399549958912$$
$$z_{51} = -10.8111042087213$$
$$z_{52} = -20.3220161353369$$
$$z_{53} = 58.0850352160434$$
$$z_{54} = 61.2283950657729$$
$$z_{55} = 51.7976718062027$$
$$z_{56} = 36.0728864084812$$
$$z_{57} = 95.7976993646524$$
$$z_{58} = 472.805464302016$$
$$z_{59} = 92.6553987604331$$
$$z_{60} = -80.0856406984281$$
$$z_{61} = -29.7779917432681$$
$$z_{62} = 48.6535849776189$$
$$z_{63} = 7.59205618191083$$
$$z_{64} = -120.934779700424$$
$$z_{65} = 136.644644187573$$
$$z_{66} = -23.4768059032848$$
Signos de extremos en los puntos:
(-51.79767180620269, -0.000372578407377583)
(-58.08503521604338, -0.000296307594083531)
(-61.22839506577286, 0.000266672614366939)
(73.80032886750858, -0.000183570831307369)
(-42.36430002784626, 0.000556875375921231)
(-36.072886408481175, 0.000767899860645288)
(86.37064299222264, -0.000134032303380199)
(-83.22817615286866, -0.000144343274284351)
(32.925999256789495, 0.00092155585086097)
(80.0856406984281, -0.000155891696428242)
(-4.250231984043597, 0.0524535903376383)
(29.777991743268093, -0.0011264701660197)
(26.62846523778512, 0.00140830162078119)
(-73.80032886750858, 0.000183570831307369)
(-32.925999256789495, -0.00092155585086097)
(-98.93995499589117, 0.000102143849300632)
(42.36430002784626, -0.000556875375921231)
(20.322016135336863, 0.0024155503091525)
(-67.51462100515869, 0.000219335568761136)
(-64.37158228690171, -0.000241271950626197)
(-39.2189234266452, -0.000649720249572517)
(67.51462100515869, -0.000219335568761136)
(23.476805903284752, -0.00181106789272178)
(64.37158228690171, 0.000241271950626197)
(-86.37064299222264, 0.000134032303380199)
(-70.65753104935389, -0.000200260872068306)
(-89.5130484454873, -0.000124788081105762)
(-26.62846523778512, -0.00140830162078119)
(-7.592056181910829, -0.0170534046093743)
(-95.79769936465237, -0.000108953834823294)
(39.2189234266452, 0.000649720249572517)
(89.5130484454873, 0.000124788081105762)
(-17.162357097018344, 0.00338356230302691)
(76.94302821811836, 0.000168883841534665)
(4.250231984043597, -0.0524535903376383)
(-212.0480723636933, 2.22393292118406e-5)
(10.811104208721284, -0.00848320511338927)
(-92.65539876043312, 0.000116468359027335)
(17.162357097018344, -0.00338356230302691)
(83.22817615286866, 0.000144343274284351)
(-45.509153345156335, -0.000482606141533831)
(54.941473083787834, -0.00033117347900486)
(-76.94302821811836, -0.000168883841534665)
(13.994496112690735, 0.00508011541536346)
(-54.941473083787834, 0.00033117347900486)
(-48.653584977618934, 0.000422266745161591)
(45.509153345156335, 0.000482606141533831)
(-13.994496112690735, -0.00508011541536346)
(70.65753104935389, 0.000200260872068306)
(98.93995499589117, -0.000102143849300632)
(-10.811104208721284, 0.00848320511338927)
(-20.322016135336863, -0.0024155503091525)
(58.08503521604338, 0.000296307594083531)
(61.22839506577286, -0.000266672614366939)
(51.79767180620269, 0.000372578407377583)
(36.072886408481175, -0.000767899860645288)
(95.79769936465237, 0.000108953834823294)
(472.8054643020164, 4.47335209914827e-6)
(92.65539876043312, -0.000116468359027335)
(-80.0856406984281, 0.000155891696428242)
(-29.777991743268093, 0.0011264701660197)
(48.653584977618934, -0.000422266745161591)
(7.592056181910829, 0.0170534046093743)
(-120.93477970042365, -6.83703606024318e-5)
(136.6446441875733, -5.35539505172292e-5)
(-23.476805903284752, 0.00181106789272178)
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:
$$z_{1} = -51.7976718062027$$
$$z_{2} = -58.0850352160434$$
$$z_{3} = 73.8003288675086$$
$$z_{4} = 86.3706429922226$$
$$z_{5} = -83.2281761528687$$
$$z_{6} = 80.0856406984281$$
$$z_{7} = 29.7779917432681$$
$$z_{8} = -32.9259992567895$$
$$z_{9} = 42.3643000278463$$
$$z_{10} = -64.3715822869017$$
$$z_{11} = -39.2189234266452$$
$$z_{12} = 67.5146210051587$$
$$z_{13} = 23.4768059032848$$
$$z_{14} = -70.6575310493539$$
$$z_{15} = -89.5130484454873$$
$$z_{16} = -26.6284652377851$$
$$z_{17} = -7.59205618191083$$
$$z_{18} = -95.7976993646524$$
$$z_{19} = 4.2502319840436$$
$$z_{20} = 10.8111042087213$$
$$z_{21} = 17.1623570970183$$
$$z_{22} = -45.5091533451563$$
$$z_{23} = 54.9414730837878$$
$$z_{24} = -76.9430282181184$$
$$z_{25} = -13.9944961126907$$
$$z_{26} = 98.9399549958912$$
$$z_{27} = -20.3220161353369$$
$$z_{28} = 61.2283950657729$$
$$z_{29} = 36.0728864084812$$
$$z_{30} = 92.6553987604331$$
$$z_{31} = 48.6535849776189$$
$$z_{32} = -120.934779700424$$
$$z_{33} = 136.644644187573$$
Puntos máximos de la función:
$$z_{33} = -61.2283950657729$$
$$z_{33} = -42.3643000278463$$
$$z_{33} = -36.0728864084812$$
$$z_{33} = 32.9259992567895$$
$$z_{33} = -4.2502319840436$$
$$z_{33} = 26.6284652377851$$
$$z_{33} = -73.8003288675086$$
$$z_{33} = -98.9399549958912$$
$$z_{33} = 20.3220161353369$$
$$z_{33} = -67.5146210051587$$
$$z_{33} = 64.3715822869017$$
$$z_{33} = -86.3706429922226$$
$$z_{33} = 39.2189234266452$$
$$z_{33} = 89.5130484454873$$
$$z_{33} = -17.1623570970183$$
$$z_{33} = 76.9430282181184$$
$$z_{33} = -212.048072363693$$
$$z_{33} = -92.6553987604331$$
$$z_{33} = 83.2281761528687$$
$$z_{33} = 13.9944961126907$$
$$z_{33} = -54.9414730837878$$
$$z_{33} = -48.6535849776189$$
$$z_{33} = 45.5091533451563$$
$$z_{33} = 70.6575310493539$$
$$z_{33} = -10.8111042087213$$
$$z_{33} = 58.0850352160434$$
$$z_{33} = 51.7976718062027$$
$$z_{33} = 95.7976993646524$$
$$z_{33} = 472.805464302016$$
$$z_{33} = -80.0856406984281$$
$$z_{33} = -29.7779917432681$$
$$z_{33} = 7.59205618191083$$
$$z_{33} = -23.4768059032848$$
Decrece en los intervalos
$$\left[136.644644187573, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -120.934779700424\right]$$