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$$- \left(x + 3\right) \sin{\left(x \right)} + \cos{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -59.7078928202273$$
$$x_{2} = 84.8343862178182$$
$$x_{3} = -97.3999650893223$$
$$x_{4} = -87.9763617358531$$
$$x_{5} = 59.7062064512464$$
$$x_{6} = -100.541216632062$$
$$x_{7} = -37.7278991803885$$
$$x_{8} = -56.567333690088$$
$$x_{9} = 34.5841198954721$$
$$x_{10} = 3.29903328785148$$
$$x_{11} = -50.2866269338091$$
$$x_{12} = -47.1465377637573$$
$$x_{13} = -40.8671065042713$$
$$x_{14} = -72.2710660715932$$
$$x_{15} = 31.4449502153243$$
$$x_{16} = -81.6941157398245$$
$$x_{17} = -25.1778008415242$$
$$x_{18} = -94.2587370240534$$
$$x_{19} = 47.1438297937958$$
$$x_{20} = -44.0066785894522$$
$$x_{21} = 91.1168116486103$$
$$x_{22} = 97.3993321575476$$
$$x_{23} = -75.4120326678904$$
$$x_{24} = 50.2842475271843$$
$$x_{25} = 75.4109763113185$$
$$x_{26} = 94.2580611694573$$
$$x_{27} = 78.5520778284944$$
$$x_{28} = 40.8634985472455$$
$$x_{29} = -91.1175349460173$$
$$x_{30} = -15.786014834861$$
$$x_{31} = -12.6694230459213$$
$$x_{32} = -9.57569676385338$$
$$x_{33} = -28.3138174685366$$
$$x_{34} = -34.5891650451544$$
$$x_{35} = -18.912317780113$$
$$x_{36} = -69.130158920116$$
$$x_{37} = 87.9755858178486$$
$$x_{38} = -22.0436114382877$$
$$x_{39} = -65.9893200989848$$
$$x_{40} = -78.5530512997373$$
$$x_{41} = -3.95172192033919$$
$$x_{42} = 37.7236626573345$$
$$x_{43} = -53.4269031964768$$
$$x_{44} = 0.294682454486773$$
$$x_{45} = 56.5654544420077$$
$$x_{46} = 213.632916514985$$
$$x_{47} = 15.7612143304042$$
$$x_{48} = -2.22814103089124$$
$$x_{49} = 53.4247959606036$$
$$x_{50} = 6.38928965648362$$
$$x_{51} = 28.30626551274$$
$$x_{52} = 100.540622659664$$
$$x_{53} = 72.2699157713744$$
$$x_{54} = 22.0310776789363$$
$$x_{55} = 25.1682273173293$$
$$x_{56} = -6.55723006500106$$
$$x_{57} = 9.50457883886398$$
$$x_{58} = 69.1289015588518$$
$$x_{59} = -31.4510601479335$$
$$x_{60} = -62.8485603567807$$
$$x_{61} = 18.8951963232073$$
$$x_{62} = 12.6302619891586$$
$$x_{63} = -84.835220716198$$
$$x_{64} = 44.0035689215071$$
$$x_{65} = 65.9879399974437$$
$$x_{66} = 62.8470386162472$$
$$x_{67} = 81.6932157658594$$
Signos de extremos en los puntos:
(-59.707892820227336, 56.6990777612809)
(84.83438621781819, -87.828694239774)
(-97.39996508932231, 94.3946689229274)
(-87.97636173585312, -84.9704783576549)
(59.70620645124642, -62.6982342794497)
(-100.54121663206242, -97.5360909979324)
(-37.7278991803885, -34.7135104817292)
(-56.56733369008799, -53.558002082243)
(34.58411989547207, -37.5708234637983)
(3.299033287851476, -6.22112560417095)
(-50.28662693380906, -47.2760566650762)
(-47.14653776375731, 44.1352162039481)
(-40.867106504271284, 37.8539093345704)
(-72.2710660715932, 69.2638491787087)
(31.444950215324322, 34.4304434690237)
(-81.69411573982451, -78.6877627940051)
(-25.177800841524213, -22.15529009427)
(-94.25873702405337, -91.2532585899567)
(47.14382979379579, -50.1338614505173)
(-44.006678589452186, -40.9944908893309)
(91.1168116486103, -94.1114995512231)
(97.39933215754765, -100.394352415252)
(-75.41203266789043, -72.4051287256054)
(50.28424752718431, 53.2748663689057)
(75.41097631131846, 78.4046004308088)
(94.25806116945732, 97.2529206150062)
(78.55207782849438, -81.545947468169)
(40.863498547245456, -43.8521039892383)
(-91.11753494601734, 88.1118612545098)
(-15.786014834860985, 12.7470881005591)
(-12.669423045921281, -9.61812478108002)
(-9.575696763853385, 6.50095316217611)
(-28.31381746853661, 25.2940884985806)
(-34.589165045154424, 31.5733487197023)
(-18.91231778011301, -15.8809883513863)
(-69.13015892011602, -66.1225993697551)
(87.97558581784861, 90.9700903358314)
(-22.043611438287677, 19.0174100876084)
(-65.98932009898483, 62.9813837455716)
(-78.55305129973732, 75.5464343027166)
(-3.951721920339186, 0.656121661044172)
(37.72366265733454, 40.7113903330478)
(-53.42690319647679, 50.4169907777953)
(0.2946824544867733, 3.15266324719375)
(56.56545444200766, 59.5570620887982)
(213.6329165149846, 216.630608500037)
(15.761214330404183, -18.7346202562976)
(-2.228141030891238, -0.471618974793956)
(53.424795960603625, -56.4159366951519)
(6.389289656483623, 9.33648628773909)
(28.30626551273998, -31.2903064803893)
(100.5406226596642, 103.535793974935)
(72.26991577137444, -75.2632738904155)
(22.031077678936263, -25.0111263891723)
(25.168227317329272, 28.1504935824352)
(-6.557230065001062, -3.42448900708588)
(9.504578838863976, -12.4647842585051)
(69.1289015588518, 72.121970523981)
(-31.45106014793351, -28.4335023766721)
(-62.84856035678067, -59.840207685858)
(18.895196323207266, 21.8723959280207)
(12.63026198915859, 15.59837063305)
(-84.83522071619804, 81.8291115616385)
(44.00356892150712, 46.9929350411195)
(65.98793999744368, -68.9806934957898)
(62.84703861624724, 65.8394465735594)
(81.69321576585943, 84.6873127224841)
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:
$$x_{1} = 84.8343862178182$$
$$x_{2} = -87.9763617358531$$
$$x_{3} = 59.7062064512464$$
$$x_{4} = -100.541216632062$$
$$x_{5} = -37.7278991803885$$
$$x_{6} = -56.567333690088$$
$$x_{7} = 34.5841198954721$$
$$x_{8} = 3.29903328785148$$
$$x_{9} = -50.2866269338091$$
$$x_{10} = -81.6941157398245$$
$$x_{11} = -25.1778008415242$$
$$x_{12} = -94.2587370240534$$
$$x_{13} = 47.1438297937958$$
$$x_{14} = -44.0066785894522$$
$$x_{15} = 91.1168116486103$$
$$x_{16} = 97.3993321575476$$
$$x_{17} = -75.4120326678904$$
$$x_{18} = 78.5520778284944$$
$$x_{19} = 40.8634985472455$$
$$x_{20} = -12.6694230459213$$
$$x_{21} = -18.912317780113$$
$$x_{22} = -69.130158920116$$
$$x_{23} = 15.7612143304042$$
$$x_{24} = -2.22814103089124$$
$$x_{25} = 53.4247959606036$$
$$x_{26} = 28.30626551274$$
$$x_{27} = 72.2699157713744$$
$$x_{28} = 22.0310776789363$$
$$x_{29} = -6.55723006500106$$
$$x_{30} = 9.50457883886398$$
$$x_{31} = -31.4510601479335$$
$$x_{32} = -62.8485603567807$$
$$x_{33} = 65.9879399974437$$
Puntos máximos de la función:
$$x_{33} = -59.7078928202273$$
$$x_{33} = -97.3999650893223$$
$$x_{33} = -47.1465377637573$$
$$x_{33} = -40.8671065042713$$
$$x_{33} = -72.2710660715932$$
$$x_{33} = 31.4449502153243$$
$$x_{33} = 50.2842475271843$$
$$x_{33} = 75.4109763113185$$
$$x_{33} = 94.2580611694573$$
$$x_{33} = -91.1175349460173$$
$$x_{33} = -15.786014834861$$
$$x_{33} = -9.57569676385338$$
$$x_{33} = -28.3138174685366$$
$$x_{33} = -34.5891650451544$$
$$x_{33} = 87.9755858178486$$
$$x_{33} = -22.0436114382877$$
$$x_{33} = -65.9893200989848$$
$$x_{33} = -78.5530512997373$$
$$x_{33} = -3.95172192033919$$
$$x_{33} = 37.7236626573345$$
$$x_{33} = -53.4269031964768$$
$$x_{33} = 0.294682454486773$$
$$x_{33} = 56.5654544420077$$
$$x_{33} = 213.632916514985$$
$$x_{33} = 6.38928965648362$$
$$x_{33} = 100.540622659664$$
$$x_{33} = 25.1682273173293$$
$$x_{33} = 69.1289015588518$$
$$x_{33} = 18.8951963232073$$
$$x_{33} = 12.6302619891586$$
$$x_{33} = -84.835220716198$$
$$x_{33} = 44.0035689215071$$
$$x_{33} = 62.8470386162472$$
$$x_{33} = 81.6932157658594$$
Decrece en los intervalos
$$\left[97.3993321575476, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -100.541216632062\right]$$