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$$3 \left(2 - x\right) \cos{\left(3 x \right)} - \sin{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 9.96232320225281$$
$$x_{2} = -67.5458397072056$$
$$x_{3} = -80.1119658249941$$
$$x_{4} = 20.4263815923276$$
$$x_{5} = 80.1120351161852$$
$$x_{6} = 58.1214439015663$$
$$x_{7} = 60.2157677814793$$
$$x_{8} = -84.3006903530151$$
$$x_{9} = 22.5201616033877$$
$$x_{10} = -9.95766637034931$$
$$x_{11} = 3.72868699197556$$
$$x_{12} = -25.660356790279$$
$$x_{13} = 36.1315707892235$$
$$x_{14} = -45.5554298935609$$
$$x_{15} = 88.4894777475417$$
$$x_{16} = 51.8385081738833$$
$$x_{17} = -59.1684781012596$$
$$x_{18} = 75.92332551045$$
$$x_{19} = 29.8491197716614$$
$$x_{20} = 67.545937201537$$
$$x_{21} = -3.68471466585212$$
$$x_{22} = 23.5670963726253$$
$$x_{23} = -17.2845206944998$$
$$x_{24} = -12.0506782381102$$
$$x_{25} = 66.4987671714594$$
$$x_{26} = 82.2063930758537$$
$$x_{27} = -47.6497264455869$$
$$x_{28} = -60.2156450797795$$
$$x_{29} = 97.9141294758355$$
$$x_{30} = -43.4611424205861$$
$$x_{31} = -56.026983785923$$
$$x_{32} = -51.8383425493131$$
$$x_{33} = -82.2063272722808$$
$$x_{34} = 14.1463123695534$$
$$x_{35} = 31.9432358831278$$
$$x_{36} = 12.0538194238034$$
$$x_{37} = 2.04735493915155$$
$$x_{38} = -49.7440309744258$$
$$x_{39} = 93.7253921719368$$
$$x_{40} = 89.5366599306405$$
$$x_{41} = -58.1213121876782$$
$$x_{42} = -78.0176061394084$$
$$x_{43} = 92.6782086095896$$
$$x_{44} = -27.7544692167826$$
$$x_{45} = -95.8197118065843$$
$$x_{46} = -16.2376537668883$$
$$x_{47} = -73.8288926371925$$
$$x_{48} = -89.5366044654302$$
$$x_{49} = 73.8289742325362$$
$$x_{50} = -65.4514942106512$$
$$x_{51} = 18.3327591618833$$
$$x_{52} = 42.4142500664018$$
$$x_{53} = -36.1312293557476$$
$$x_{54} = -87.4422377858371$$
$$x_{55} = -14.144048444639$$
$$x_{56} = -71.7345391539446$$
$$x_{57} = 38.2257777157102$$
$$x_{58} = -53.9326603788633$$
$$x_{59} = 5.78883713314295$$
$$x_{60} = -7.86524024026489$$
$$x_{61} = 100.008499823424$$
$$x_{62} = -23.5662906561567$$
$$x_{63} = 53.9328133737445$$
$$x_{64} = 40.3200052068117$$
$$x_{65} = -41.3668653417664$$
$$x_{66} = 86.3951145254411$$
$$x_{67} = -13.0973278485316$$
$$x_{68} = 56.0271255430209$$
$$x_{69} = 27.7550490145464$$
$$x_{70} = -1.60155952067584$$
$$x_{71} = 71.7346255868793$$
$$x_{72} = -38.2254727631659$$
$$x_{73} = -31.9427986874028$$
$$x_{74} = 44.5085097279974$$
$$x_{75} = 7.87288071138934$$
$$x_{76} = 62.3100966076178$$
$$x_{77} = -69.6401881040092$$
$$x_{78} = 34.0373884587993$$
$$x_{79} = -97.9140830993203$$
$$x_{80} = 84.300752925847$$
$$x_{81} = 26.7080342455312$$
$$x_{82} = -34.0370035765122$$
$$x_{83} = -21.4722831968623$$
$$x_{84} = 64.4044298820374$$
$$x_{85} = -91.6309724165308$$
$$x_{86} = -5.77387067588387$$
$$x_{87} = 49.7442108604397$$
$$x_{88} = 16.2393637138968$$
$$x_{89} = 78.0176792030724$$
$$x_{90} = -93.7253415556846$$
$$x_{91} = 0.452862821774091$$
$$x_{92} = 95.8197602334393$$
$$x_{93} = -28.8015398403524$$
$$x_{94} = -100.008455369724$$
$$x_{95} = -29.8486188079329$$
$$x_{96} = -75.923248357564$$
Signos de extremos en los puntos:
(9.96232320225281, 7.95535505533626)
(-67.54583970720556, -69.5450408873393)
(-80.11196582499414, -82.1112892504126)
(20.426381592327598, 18.4233673312992)
(80.11203511618517, -78.1113238967589)
(58.12144390156634, 56.120454011039)
(60.21576778147927, 58.2148135006776)
(-84.30069035301509, -86.3000466161721)
(22.520161603387688, 20.5174547746447)
(-9.957666370349314, 11.953023056467)
(3.7286869919755623, 1.69741885326769)
(-25.66035679027901, -27.6583485188146)
(36.131570789223545, -34.129943217432)
(-45.5554298935609, 47.5542617092204)
(88.48947774754166, -86.4888354158024)
(51.83850817388331, 49.8373934998333)
(-59.16847810125964, -61.1675698831714)
(75.92332551044996, -73.9225739924684)
(29.849119771661385, -27.8471251094449)
(67.54593720153701, -65.545089635992)
(-3.6847146658521206, 5.67496699921425)
(23.567096372625265, -21.5645208936005)
(-17.284520694499847, -19.2816405031431)
(-12.050678238110196, 14.0467259651216)
(66.49876717145945, 64.497905845807)
(82.2063930758537, -80.205700427378)
(-47.64972644558691, 49.6486075335298)
(-60.21564507977946, 62.2147521474717)
(97.91412947583547, 95.9135502592736)
(-43.461142420586114, 45.4599204249959)
(-56.02698378592297, 58.0260264006339)
(-51.83834254931308, 53.8373106832533)
(-82.20632727228079, -84.2056675249144)
(14.146312369553405, 12.1417410895444)
(31.94323588312782, -29.9413806931026)
(12.053819423803384, 10.0482981593795)
(2.0473549391515533, 0.00666059312023594)
(-49.744030974425755, 51.7429573466962)
(93.72539217193679, 91.7247865053489)
(89.53665993064048, 87.5360252828092)
(-58.12131218767819, 60.1203881513799)
(-78.01760613940837, -80.0169118567975)
(92.67820860958963, -90.6775959486938)
(-27.754469216782628, -29.7526022593713)
(-95.81971180658431, 97.8191438732843)
(-16.237653766888325, 18.2346083290743)
(-73.82889263719245, -75.8281600041751)
(-89.53660446543022, 91.535997549723)
(73.8289742325362, -71.8282008028883)
(-65.45149421065119, -67.4506705886001)
(18.332759161883278, 16.3293587439915)
(42.414250066401806, -40.4128754838939)
(-36.13122935574756, -38.1297724824022)
(-87.44223778583712, 89.441616658971)
(-14.14404844463899, 16.1406083039055)
(-71.73453915394457, -73.7337857118716)
(38.22577771571016, -36.2242442212912)
(-53.93266037886334, 55.9316671474422)
(5.788837133142952, 3.77425875029453)
(-7.865240240264894, 9.85961361286801)
(100.00849982342389, 98.0079329840815)
(-23.56629065615666, -25.5641179329247)
(53.93281337374453, 51.9317436485471)
(40.32000520681172, -38.3185555096453)
(-41.36686534176637, 43.3655843385496)
(86.39511452544113, -84.394456253859)
(-13.097327848531625, -15.0936493663082)
(56.027125543020915, 54.0260972823282)
(27.7550490145464, -25.7528922111544)
(-1.6015595206758413, 3.58623250224175)
(71.73462558687933, -69.7338289295075)
(-38.22547276316586, -40.2240917304338)
(-31.9427986874028, -33.9411620652135)
(44.50850972799743, -42.507202860409)
(7.872880711389341, 5.86344382864429)
(62.310096607617844, 60.3091754636321)
(-69.6401881040092, -71.6394126362866)
(34.037388458799306, -32.035654514553)
(-97.91408309932031, 99.9135270706797)
(84.30075292584702, -82.3000779032003)
(26.708034245531216, 24.7057860710042)
(-34.03700357651216, -36.0354620501536)
(-21.472283196862282, -23.469916697043)
(64.4044298820374, 62.4035396508972)
(-91.63097241653075, 93.6303790762499)
(-5.773870675883874, 7.76673406820216)
(49.74421086043972, 47.7430472947705)
(16.239363713896832, 14.2354637690691)
(78.01767920307245, -76.0169483894644)
(-93.7253415556846, 95.7247611968222)
(0.4528628217740906, 1.51243223138301)
(95.81976023343928, 93.8191680870785)
(-28.801539840352447, 30.7997363371339)
(-100.008455369724, 102.007910756923)
(-29.848618807932944, -31.8468745881254)
(-75.92324835756396, -77.9225354150945)
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:
$$x_{1} = -67.5458397072056$$
$$x_{2} = -80.1119658249941$$
$$x_{3} = 80.1120351161852$$
$$x_{4} = -84.3006903530151$$
$$x_{5} = -25.660356790279$$
$$x_{6} = 36.1315707892235$$
$$x_{7} = 88.4894777475417$$
$$x_{8} = -59.1684781012596$$
$$x_{9} = 75.92332551045$$
$$x_{10} = 29.8491197716614$$
$$x_{11} = 67.545937201537$$
$$x_{12} = 23.5670963726253$$
$$x_{13} = -17.2845206944998$$
$$x_{14} = 82.2063930758537$$
$$x_{15} = -82.2063272722808$$
$$x_{16} = 31.9432358831278$$
$$x_{17} = -78.0176061394084$$
$$x_{18} = 92.6782086095896$$
$$x_{19} = -27.7544692167826$$
$$x_{20} = -73.8288926371925$$
$$x_{21} = 73.8289742325362$$
$$x_{22} = -65.4514942106512$$
$$x_{23} = 42.4142500664018$$
$$x_{24} = -36.1312293557476$$
$$x_{25} = -71.7345391539446$$
$$x_{26} = 38.2257777157102$$
$$x_{27} = -23.5662906561567$$
$$x_{28} = 40.3200052068117$$
$$x_{29} = 86.3951145254411$$
$$x_{30} = -13.0973278485316$$
$$x_{31} = 27.7550490145464$$
$$x_{32} = 71.7346255868793$$
$$x_{33} = -38.2254727631659$$
$$x_{34} = -31.9427986874028$$
$$x_{35} = 44.5085097279974$$
$$x_{36} = -69.6401881040092$$
$$x_{37} = 34.0373884587993$$
$$x_{38} = 84.300752925847$$
$$x_{39} = -34.0370035765122$$
$$x_{40} = -21.4722831968623$$
$$x_{41} = 78.0176792030724$$
$$x_{42} = -29.8486188079329$$
$$x_{43} = -75.923248357564$$
Puntos máximos de la función:
$$x_{43} = 9.96232320225281$$
$$x_{43} = 20.4263815923276$$
$$x_{43} = 58.1214439015663$$
$$x_{43} = 60.2157677814793$$
$$x_{43} = 22.5201616033877$$
$$x_{43} = -9.95766637034931$$
$$x_{43} = 3.72868699197556$$
$$x_{43} = -45.5554298935609$$
$$x_{43} = 51.8385081738833$$
$$x_{43} = -3.68471466585212$$
$$x_{43} = -12.0506782381102$$
$$x_{43} = 66.4987671714594$$
$$x_{43} = -47.6497264455869$$
$$x_{43} = -60.2156450797795$$
$$x_{43} = 97.9141294758355$$
$$x_{43} = -43.4611424205861$$
$$x_{43} = -56.026983785923$$
$$x_{43} = -51.8383425493131$$
$$x_{43} = 14.1463123695534$$
$$x_{43} = 12.0538194238034$$
$$x_{43} = 2.04735493915155$$
$$x_{43} = -49.7440309744258$$
$$x_{43} = 93.7253921719368$$
$$x_{43} = 89.5366599306405$$
$$x_{43} = -58.1213121876782$$
$$x_{43} = -95.8197118065843$$
$$x_{43} = -16.2376537668883$$
$$x_{43} = -89.5366044654302$$
$$x_{43} = 18.3327591618833$$
$$x_{43} = -87.4422377858371$$
$$x_{43} = -14.144048444639$$
$$x_{43} = -53.9326603788633$$
$$x_{43} = 5.78883713314295$$
$$x_{43} = -7.86524024026489$$
$$x_{43} = 100.008499823424$$
$$x_{43} = 53.9328133737445$$
$$x_{43} = -41.3668653417664$$
$$x_{43} = 56.0271255430209$$
$$x_{43} = -1.60155952067584$$
$$x_{43} = 7.87288071138934$$
$$x_{43} = 62.3100966076178$$
$$x_{43} = -97.9140830993203$$
$$x_{43} = 26.7080342455312$$
$$x_{43} = 64.4044298820374$$
$$x_{43} = -91.6309724165308$$
$$x_{43} = -5.77387067588387$$
$$x_{43} = 49.7442108604397$$
$$x_{43} = 16.2393637138968$$
$$x_{43} = -93.7253415556846$$
$$x_{43} = 0.452862821774091$$
$$x_{43} = 95.8197602334393$$
$$x_{43} = -28.8015398403524$$
$$x_{43} = -100.008455369724$$
Decrece en los intervalos
$$\left[92.6782086095896, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -84.3006903530151\right]$$