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$$- x \sin{\left(x \right)} + 2 \cos{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 69.1439554764926$$
$$x_{2} = -1.0768739863118$$
$$x_{3} = -47.1662676027767$$
$$x_{4} = 15.8336114149477$$
$$x_{5} = 25.2119030642106$$
$$x_{6} = 18.954681766529$$
$$x_{7} = 1.0768739863118$$
$$x_{8} = -18.954681766529$$
$$x_{9} = -84.8465692433091$$
$$x_{10} = -25.2119030642106$$
$$x_{11} = 34.6152330552306$$
$$x_{12} = -40.8895777660408$$
$$x_{13} = 62.863657228703$$
$$x_{14} = -81.7058821480364$$
$$x_{15} = 44.0276918992479$$
$$x_{16} = -66.0037377708277$$
$$x_{17} = 100.550852725424$$
$$x_{18} = 31.479374920314$$
$$x_{19} = -91.1281305511393$$
$$x_{20} = -100.550852725424$$
$$x_{21} = 40.8895777660408$$
$$x_{22} = 91.1281305511393$$
$$x_{23} = -59.7237354324305$$
$$x_{24} = -97.4099011706723$$
$$x_{25} = 66.0037377708277$$
$$x_{26} = -34.6152330552306$$
$$x_{27} = 12.7222987717666$$
$$x_{28} = 81.7058821480364$$
$$x_{29} = -53.4444796697636$$
$$x_{30} = 50.3052188363296$$
$$x_{31} = -62.863657228703$$
$$x_{32} = -31.479374920314$$
$$x_{33} = -9.62956034329743$$
$$x_{34} = -78.5652673845995$$
$$x_{35} = -50.3052188363296$$
$$x_{36} = -94.2689923093066$$
$$x_{37} = -28.3447768697864$$
$$x_{38} = 28.3447768697864$$
$$x_{39} = 84.8465692433091$$
$$x_{40} = 47.1662676027767$$
$$x_{41} = -69.1439554764926$$
$$x_{42} = 78.5652673845995$$
$$x_{43} = -6.57833373272234$$
$$x_{44} = -44.0276918992479$$
$$x_{45} = 9.62956034329743$$
$$x_{46} = 75.4247339745236$$
$$x_{47} = -75.4247339745236$$
$$x_{48} = 6.57833373272234$$
$$x_{49} = -128.820822990274$$
$$x_{50} = -72.2842925036825$$
$$x_{51} = -37.7520396346102$$
$$x_{52} = 87.9873209346887$$
$$x_{53} = 72.2842925036825$$
$$x_{54} = 97.4099011706723$$
$$x_{55} = 3.6435971674254$$
$$x_{56} = 59.7237354324305$$
$$x_{57} = 53.4444796697636$$
$$x_{58} = -3.6435971674254$$
$$x_{59} = -22.0814757672807$$
$$x_{60} = 94.2689923093066$$
$$x_{61} = -56.5839987378634$$
$$x_{62} = -12.7222987717666$$
$$x_{63} = -87.9873209346887$$
$$x_{64} = 56.5839987378634$$
$$x_{65} = -15.8336114149477$$
$$x_{66} = 37.7520396346102$$
$$x_{67} = 22.0814757672807$$
Signos de extremos en los puntos:
(69.1439554764926, 69.1439615216012)
(-1.0768739863118038, -1.39100784545588)
(-47.1662676027767, 47.1662866291145)
(15.833611414947718, -15.834107331638)
(25.21190306421058, 25.2120270830452)
(18.954681766529042, 18.9549722147554)
(1.0768739863118038, 1.39100784545588)
(-18.954681766529042, -18.9549722147554)
(-84.84656924330915, 84.8465725158561)
(-25.21190306421058, -25.2120270830452)
(34.61523305523058, -34.6152811148717)
(-40.889577766040844, 40.8896069506711)
(62.863657228703005, 62.8636652712142)
(-81.70588214803641, -81.7058858124955)
(44.02769189924788, 44.0277152852979)
(-66.00373777082767, 66.0037447198836)
(100.55085272542402, 100.550854691956)
(31.479374920314047, 31.4794387763188)
(-91.1281305511393, 91.1281331927175)
(-100.55085272542402, -100.550854691956)
(40.889577766040844, -40.8896069506711)
(91.1281305511393, -91.1281331927175)
(-59.72373543243046, 59.7237448102597)
(-97.40990117067226, 97.4099033335782)
(66.00373777082767, -66.0037447198836)
(-34.61523305523058, 34.6152811148717)
(12.722298771766635, 12.7232465674385)
(81.70588214803641, 81.7058858124955)
(-53.44447966976355, 53.4444927529527)
(50.30521883632959, 50.3052345220647)
(-62.863657228703005, -62.8636652712142)
(-31.479374920314047, -31.4794387763188)
(-9.62956034329743, 9.63170728857969)
(-78.56526738459954, 78.5652715061143)
(-50.30521883632959, -50.3052345220647)
(-94.26899230930657, -94.2689946956226)
(-28.344776869786372, 28.3448642580985)
(28.344776869786372, -28.3448642580985)
(84.84656924330915, -84.8465725158561)
(47.1662676027767, -47.1662866291145)
(-69.1439554764926, -69.1439615216012)
(78.56526738459954, -78.5652715061143)
(-6.578333732722339, -6.58476172355643)
(-44.02769189924788, -44.0277152852979)
(9.62956034329743, -9.63170728857969)
(75.4247339745236, 75.4247386323507)
(-75.4247339745236, -75.4247386323507)
(6.578333732722339, 6.58476172355643)
(-128.8208229902735, 128.820823925608)
(-72.2842925036825, 72.2842977950245)
(-37.75203963461023, -37.7520767019434)
(87.9873209346887, 87.9873238692648)
(72.2842925036825, -72.2842977950245)
(97.40990117067226, -97.4099033335782)
(3.643597167425401, -3.67523306366032)
(59.72373543243046, -59.7237448102597)
(53.44447966976355, -53.4444927529527)
(-3.643597167425401, 3.67523306366032)
(-22.081475767280747, 22.0816600122592)
(94.26899230930657, 94.2689946956226)
(-56.58399873786344, -56.5840097635798)
(-12.722298771766635, -12.7232465674385)
(-87.9873209346887, -87.9873238692648)
(56.58399873786344, 56.5840097635798)
(-15.833611414947718, 15.834107331638)
(37.75203963461023, 37.7520767019434)
(22.081475767280747, -22.0816600122592)
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:
$$x_{1} = -1.0768739863118$$
$$x_{2} = 15.8336114149477$$
$$x_{3} = -18.954681766529$$
$$x_{4} = -25.2119030642106$$
$$x_{5} = 34.6152330552306$$
$$x_{6} = -81.7058821480364$$
$$x_{7} = -100.550852725424$$
$$x_{8} = 40.8895777660408$$
$$x_{9} = 91.1281305511393$$
$$x_{10} = 66.0037377708277$$
$$x_{11} = -62.863657228703$$
$$x_{12} = -31.479374920314$$
$$x_{13} = -50.3052188363296$$
$$x_{14} = -94.2689923093066$$
$$x_{15} = 28.3447768697864$$
$$x_{16} = 84.8465692433091$$
$$x_{17} = 47.1662676027767$$
$$x_{18} = -69.1439554764926$$
$$x_{19} = 78.5652673845995$$
$$x_{20} = -6.57833373272234$$
$$x_{21} = -44.0276918992479$$
$$x_{22} = 9.62956034329743$$
$$x_{23} = -75.4247339745236$$
$$x_{24} = -37.7520396346102$$
$$x_{25} = 72.2842925036825$$
$$x_{26} = 97.4099011706723$$
$$x_{27} = 3.6435971674254$$
$$x_{28} = 59.7237354324305$$
$$x_{29} = 53.4444796697636$$
$$x_{30} = -56.5839987378634$$
$$x_{31} = -12.7222987717666$$
$$x_{32} = -87.9873209346887$$
$$x_{33} = 22.0814757672807$$
Puntos máximos de la función:
$$x_{33} = 69.1439554764926$$
$$x_{33} = -47.1662676027767$$
$$x_{33} = 25.2119030642106$$
$$x_{33} = 18.954681766529$$
$$x_{33} = 1.0768739863118$$
$$x_{33} = -84.8465692433091$$
$$x_{33} = -40.8895777660408$$
$$x_{33} = 62.863657228703$$
$$x_{33} = 44.0276918992479$$
$$x_{33} = -66.0037377708277$$
$$x_{33} = 100.550852725424$$
$$x_{33} = 31.479374920314$$
$$x_{33} = -91.1281305511393$$
$$x_{33} = -59.7237354324305$$
$$x_{33} = -97.4099011706723$$
$$x_{33} = -34.6152330552306$$
$$x_{33} = 12.7222987717666$$
$$x_{33} = 81.7058821480364$$
$$x_{33} = -53.4444796697636$$
$$x_{33} = 50.3052188363296$$
$$x_{33} = -9.62956034329743$$
$$x_{33} = -78.5652673845995$$
$$x_{33} = -28.3447768697864$$
$$x_{33} = 75.4247339745236$$
$$x_{33} = 6.57833373272234$$
$$x_{33} = -128.820822990274$$
$$x_{33} = -72.2842925036825$$
$$x_{33} = 87.9873209346887$$
$$x_{33} = -3.6435971674254$$
$$x_{33} = -22.0814757672807$$
$$x_{33} = 94.2689923093066$$
$$x_{33} = 56.5839987378634$$
$$x_{33} = -15.8336114149477$$
$$x_{33} = 37.7520396346102$$
Decrece en los intervalos
$$\left[97.4099011706723, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -100.550852725424\right]$$