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$$- x \sin{\left(x \right)} + x \left(- x \cos{\left(x \right)} - \sin{\left(x \right)}\right) = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 89.5577188827244$$
$$x_{2} = -92.6985552433969$$
$$x_{3} = -29.9118938695518$$
$$x_{4} = 64.4336791037316$$
$$x_{5} = -58.153842078645$$
$$x_{6} = 23.6463238196036$$
$$x_{7} = 51.8748140534268$$
$$x_{8} = 92.6985552433969$$
$$x_{9} = 33.0471686947054$$
$$x_{10} = -80.1355651940744$$
$$x_{11} = 70.7141100665485$$
$$x_{12} = -17.3932439645948$$
$$x_{13} = 98.9803718651523$$
$$x_{14} = -70.7141100665485$$
$$x_{15} = 11.17270586833$$
$$x_{16} = 48.7357007949054$$
$$x_{17} = -89.5577188827244$$
$$x_{18} = -23.6463238196036$$
$$x_{19} = 14.2763529183365$$
$$x_{20} = 0$$
$$x_{21} = 26.7780870755585$$
$$x_{22} = -48.7357007949054$$
$$x_{23} = -55.0142096788381$$
$$x_{24} = 76.9949898891676$$
$$x_{25} = 86.4169374541167$$
$$x_{26} = 83.2762171649775$$
$$x_{27} = -61.2936749662429$$
$$x_{28} = -76.9949898891676$$
$$x_{29} = -64.4336791037316$$
$$x_{30} = -73.8545010149048$$
$$x_{31} = -14.2763529183365$$
$$x_{32} = -45.5969279840735$$
$$x_{33} = 20.5175229099417$$
$$x_{34} = -120.967848975693$$
$$x_{35} = 58.153842078645$$
$$x_{36} = 55.0142096788381$$
$$x_{37} = -51.8748140534268$$
$$x_{38} = 5.08698509410227$$
$$x_{39} = 3.95930141892882 \cdot 10^{-7}$$
$$x_{40} = 45.5969279840735$$
$$x_{41} = 73.8545010149048$$
$$x_{42} = -42.458570771699$$
$$x_{43} = -8.09616360322292$$
$$x_{44} = -36.1835330907526$$
$$x_{45} = 29.9118938695518$$
$$x_{46} = -98.9803718651523$$
$$x_{47} = 2.2889297281034$$
$$x_{48} = -11.17270586833$$
$$x_{49} = 42.458570771699$$
$$x_{50} = -83.2762171649775$$
$$x_{51} = -20.5175229099417$$
$$x_{52} = -5.08698509410227$$
$$x_{53} = 67.573830670859$$
$$x_{54} = -2.2889297281034$$
$$x_{55} = 17.3932439645948$$
$$x_{56} = -86.4169374541167$$
$$x_{57} = 36.1835330907526$$
$$x_{58} = 39.3207281322521$$
$$x_{59} = -67.573830670859$$
$$x_{60} = 80.1355651940744$$
$$x_{61} = -33.0471686947054$$
$$x_{62} = -95.839441141233$$
$$x_{63} = 95.839441141233$$
$$x_{64} = -39.3207281322521$$
$$x_{65} = 8.09616360322292$$
$$x_{66} = -26.7780870755585$$
$$x_{67} = 61.2936749662429$$
Signos de extremos en los puntos:
(89.55771888272442, -8020.58575924144)
(-92.69855524339692, -8593.02284218332)
(-29.911893869551772, -894.728075975236)
(64.43367910373156, -4151.70044687478)
(-58.153842078645, 3377.87112092779)
(23.64632381960362, 555.159297209023)
(51.874814053426775, -2690.99855997676)
(92.69855524339692, 8589.02284218332)
(33.04716869470536, -1092.12083594654)
(-80.13556519407445, -6421.70974281978)
(70.7141100665485, -5000.48656158818)
(-17.393243964594753, -302.544552657996)
(98.98037186515228, 9793.11462678078)
(-70.7141100665485, 4996.48656158818)
(11.172705868329984, 120.876173513916)
(48.73570079490539, 2371.17105456709)
(-89.55771888272442, 8016.58575924144)
(-23.64632381960362, -559.159297209023)
(14.276352918336478, -203.843217881861)
(0, -2)
(26.778087075558506, -717.074276149712)
(-48.73570079490539, -2375.17105456709)
(-55.01420967883812, -3026.56524685288)
(76.9949898891676, -5928.22947957101)
(86.4169374541167, 7463.88788203037)
(83.27621716497754, -6934.92921007843)
(-61.2936749662429, -3756.91618650696)
(-76.9949898891676, 5924.22947957101)
(-64.43367910373156, 4147.70044687478)
(-73.85450101490484, -5454.4884195005)
(-14.276352918336478, 199.843217881861)
(-45.59692798407349, 2075.08272285774)
(20.51752290994169, -420.982887272434)
(-120.96784897569329, 14629.2208957387)
(58.153842078645, -3381.87112092779)
(55.01420967883812, 3022.56524685288)
(-51.874814053426775, 2686.99855997676)
(5.08698509410227, 22.0829602230683)
(3.9593014189288195e-07, -2)
(45.59692798407349, -2079.08272285774)
(73.85450101490484, 5450.4884195005)
(-42.458570771699044, -1802.73355411815)
(-8.096163603222921, 61.6349819515545)
(-36.18353309075258, -1309.25263807613)
(29.911893869551772, 890.728075975236)
(-98.98037186515228, -9797.11462678078)
(2.2889297281034042, -5.94530162528433)
(-11.172705868329984, -124.876173513916)
(42.458570771699044, 1798.73355411815)
(-83.27621716497754, 6930.92921007843)
(-20.51752290994169, 416.982887272434)
(-5.08698509410227, -26.0829602230683)
(67.573830670859, 4562.22390457183)
(-2.2889297281034042, 1.94530162528433)
(17.393243964594753, 298.544552657996)
(-86.4169374541167, -7467.88788203037)
(36.18353309075258, 1305.25263807613)
(39.32072813225213, -1546.1235331857)
(-67.573830670859, -4566.22390457183)
(80.13556519407445, 6417.70974281978)
(-33.04716869470536, 1088.12083594654)
(-95.83944114123304, 9181.19913125177)
(95.83944114123304, -9185.19913125177)
(-39.32072813225213, 1542.1235331857)
(8.096163603222921, -65.6349819515545)
(-26.778087075558506, 713.074276149712)
(61.2936749662429, 3752.91618650696)
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:
$$x_{1} = 89.5577188827244$$
$$x_{2} = -92.6985552433969$$
$$x_{3} = -29.9118938695518$$
$$x_{4} = 64.4336791037316$$
$$x_{5} = 51.8748140534268$$
$$x_{6} = 33.0471686947054$$
$$x_{7} = -80.1355651940744$$
$$x_{8} = 70.7141100665485$$
$$x_{9} = -17.3932439645948$$
$$x_{10} = -23.6463238196036$$
$$x_{11} = 14.2763529183365$$
$$x_{12} = 26.7780870755585$$
$$x_{13} = -48.7357007949054$$
$$x_{14} = -55.0142096788381$$
$$x_{15} = 76.9949898891676$$
$$x_{16} = 83.2762171649775$$
$$x_{17} = -61.2936749662429$$
$$x_{18} = -73.8545010149048$$
$$x_{19} = 20.5175229099417$$
$$x_{20} = 58.153842078645$$
$$x_{21} = 45.5969279840735$$
$$x_{22} = -42.458570771699$$
$$x_{23} = -36.1835330907526$$
$$x_{24} = -98.9803718651523$$
$$x_{25} = 2.2889297281034$$
$$x_{26} = -11.17270586833$$
$$x_{27} = -5.08698509410227$$
$$x_{28} = -86.4169374541167$$
$$x_{29} = 39.3207281322521$$
$$x_{30} = -67.573830670859$$
$$x_{31} = 95.839441141233$$
$$x_{32} = 8.09616360322292$$
Puntos máximos de la función:
$$x_{32} = -58.153842078645$$
$$x_{32} = 23.6463238196036$$
$$x_{32} = 92.6985552433969$$
$$x_{32} = 98.9803718651523$$
$$x_{32} = -70.7141100665485$$
$$x_{32} = 11.17270586833$$
$$x_{32} = 48.7357007949054$$
$$x_{32} = -89.5577188827244$$
$$x_{32} = 86.4169374541167$$
$$x_{32} = -76.9949898891676$$
$$x_{32} = -64.4336791037316$$
$$x_{32} = -14.2763529183365$$
$$x_{32} = -45.5969279840735$$
$$x_{32} = -120.967848975693$$
$$x_{32} = 55.0142096788381$$
$$x_{32} = -51.8748140534268$$
$$x_{32} = 5.08698509410227$$
$$x_{32} = 73.8545010149048$$
$$x_{32} = -8.09616360322292$$
$$x_{32} = 29.9118938695518$$
$$x_{32} = 42.458570771699$$
$$x_{32} = -83.2762171649775$$
$$x_{32} = -20.5175229099417$$
$$x_{32} = 67.573830670859$$
$$x_{32} = -2.2889297281034$$
$$x_{32} = 17.3932439645948$$
$$x_{32} = 36.1835330907526$$
$$x_{32} = 80.1355651940744$$
$$x_{32} = -33.0471686947054$$
$$x_{32} = -95.839441141233$$
$$x_{32} = -39.3207281322521$$
$$x_{32} = -26.7780870755585$$
$$x_{32} = 61.2936749662429$$
Decrece en los intervalos
$$\left[95.839441141233, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -98.9803718651523\right]$$