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$$- 2 x^{3} \sin{\left(2 x + 1 \right)} + 3 x^{2} \cos{\left(2 x + 1 \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -53.920980767268$$
$$x_{2} = -44.4991450273812$$
$$x_{3} = -55.4913837591493$$
$$x_{4} = -63.3436910282739$$
$$x_{5} = -69.6258085806356$$
$$x_{6} = -66.4847245986491$$
$$x_{7} = 26.2320973823506$$
$$x_{8} = -19.3881624139967$$
$$x_{9} = -60.2027157509749$$
$$x_{10} = 12.1278990311653$$
$$x_{11} = -77.4786988837612$$
$$x_{12} = -3.82830914943635$$
$$x_{13} = 65.4848967454959$$
$$x_{14} = -5.34908878227838$$
$$x_{15} = -31.9393912700582$$
$$x_{16} = 7.45328197170462$$
$$x_{17} = -97.89703277248$$
$$x_{18} = 54.4916315442572$$
$$x_{19} = -74.3375151089096$$
$$x_{20} = 90.6144630226302$$
$$x_{21} = -9.99922859324132$$
$$x_{22} = 34.0795123515579$$
$$x_{23} = -47.6396278004208$$
$$x_{24} = -33.509089917422$$
$$x_{25} = -6.89036083606886$$
$$x_{26} = -27.2310518364881$$
$$x_{27} = 19.9578609060005$$
$$x_{28} = -91.6143727110982$$
$$x_{29} = -16.253975499135$$
$$x_{30} = -42.9289644405571$$
$$x_{31} = 62.3438808011978$$
$$x_{32} = 24.6631136019729$$
$$x_{33} = 56.0620426091653$$
$$x_{34} = -82.1905331189489$$
$$x_{35} = 35.6493413706884$$
$$x_{36} = 46.6399648925705$$
$$x_{37} = -17.8207464039154$$
$$x_{38} = 48.2102379751467$$
$$x_{39} = -96.3263613358694$$
$$x_{40} = 71.7670799851542$$
$$x_{41} = 87.4731675181051$$
$$x_{42} = -85.3317899632627$$
$$x_{43} = -90.0437191441857$$
$$x_{44} = 10.5660849493729$$
$$x_{45} = -8.44190646962111$$
$$x_{46} = -46.0693675258808$$
$$x_{47} = -39.7887487974318$$
$$x_{48} = 98.4677847032998$$
$$x_{49} = 85.9025279122305$$
$$x_{50} = 0$$
$$x_{51} = -52.350601348512$$
$$x_{52} = 63.9143816930814$$
$$x_{53} = 76.478825391736$$
$$x_{54} = 30.940147920832$$
$$x_{55} = 78.0494244526445$$
$$x_{56} = 21.5259340380784$$
$$x_{57} = -83.761158394026$$
$$x_{58} = 1.46875715449572$$
$$x_{59} = 5.90751476216082$$
$$x_{60} = -88.4730706441605$$
$$x_{61} = -68.0552607240211$$
$$x_{62} = -75.9081027685434$$
$$x_{63} = 13.6917269569451$$
$$x_{64} = 41.9293804173271$$
$$x_{65} = -25.6619341793609$$
$$x_{66} = -38.2187256644571$$
$$x_{67} = -41.3588305270381$$
$$x_{68} = 27.8012849208276$$
$$x_{69} = 43.4995318860771$$
$$x_{70} = -11.5600921825434$$
$$x_{71} = 84.3318941416265$$
$$x_{72} = -61.7731955478753$$
$$x_{73} = 70.1965173707413$$
$$x_{74} = 18.3902483245716$$
$$x_{75} = -99.4677081521043$$
$$x_{76} = 57.6324746505145$$
$$x_{77} = 68.6259654470392$$
$$x_{78} = 49.7805440271733$$
$$x_{79} = -24.0930341042649$$
$$x_{80} = 93.7557784321957$$
$$x_{81} = 79.6200312924209$$
$$x_{82} = 32.5097764956444$$
$$x_{83} = -0.993012768186475$$
$$x_{84} = 82.7612665383043$$
$$x_{85} = 92.1851183663932$$
$$x_{86} = 4.37745173783439$$
$$x_{87} = 40.3592790344869$$
$$x_{88} = 100.038461469597$$
$$x_{89} = -30.36980573801$$
Signos de extremos en los puntos:
(-53.92098076726796, -156713.124874719)
(-44.499145027381196, -88066.0270028243)
(-55.49138375914926, 170811.873216458)
(-63.343691028273874, -254090.463321506)
(-69.62580858063565, -337450.435998298)
(-66.4847245986491, -293802.249843683)
(26.2320973823506, -18021.4688561048)
(-19.38816241399675, -7266.3123209779)
(-60.20271575097493, -218129.038765049)
(12.12789903116531, 1770.35404671939)
(-77.47869888376118, 465013.521954895)
(-3.828309149436354, -52.2406056280508)
(65.48489674549594, 280743.388075882)
(-5.349088782278377, 147.367565407233)
(-31.939391270058206, -32546.2899216523)
(7.453281971704617, -405.901804893915)
(-97.89703277248002, -938118.309437017)
(54.491631544257196, -161742.798964074)
(-74.3375151089096, 410710.421934232)
(90.61446302263019, 743931.705622223)
(-9.99922859324132, -988.705830373094)
(34.07951235155789, 39542.1103686768)
(-47.639627800420755, -108066.206801044)
(-33.50908991742199, 37588.3456180126)
(-6.890360836068862, -319.647577148705)
(-27.23105183648813, 20162.0814889113)
(19.95786090600052, -7927.18163777416)
(-91.61437271109816, -768834.092602347)
(-16.253975499134967, -4275.99598936848)
(-42.928964440557145, 79065.3654266865)
(62.34388080119781, 242245.562880186)
(24.663113601972853, 14974.1424384835)
(56.06204260916532, 176137.307830814)
(-82.19053311894892, -555127.930240052)
(35.649341370688354, -45265.8236365594)
(46.63996489257051, 101402.84854623)
(-17.82074640391537, 5639.55242969137)
(48.21023797514666, -111997.341806469)
(-96.32636133586944, 893681.600899138)
(71.76707998515417, 369556.622145352)
(87.47316751810513, 669207.369791765)
(-85.33178996326265, -621248.679524787)
(-90.0437191441857, 729961.613250036)
(10.566084949372932, -1167.91031494736)
(-8.44190646962111, 592.341070181222)
(-46.0693675258808, 97725.222557282)
(-39.788748797431836, 62946.6253627079)
(98.46778470329984, -954623.492074991)
(85.90252791223045, -633799.12134933)
(0, 0)
(-52.35060134851196, 143412.438771775)
(63.914381693081445, -261021.455081691)
(76.47882539173604, -447239.456722941)
(30.94014792083201, 29584.0329646316)
(78.04942445264449, 475366.885553642)
(21.525934038078393, 9950.25358767486)
(-83.76115839402597, 587568.354034401)
(1.4687571544957205, -2.21674764909933)
(5.907514762160816, 199.823827221346)
(-88.47307064416049, -692422.054424836)
(-68.05526072402108, 315122.665612813)
(-75.90810276854336, -437300.157866232)
(13.691726956945134, -2551.43160066216)
(41.92938041732709, -73667.7838699325)
(-25.661934179360944, -16870.4824744167)
(-38.218725664457146, -55782.0374498392)
(-41.3588305270381, -70699.9831173598)
(27.801284920827587, 21456.7229275275)
(43.49953188607711, 82261.324289023)
(-11.560092182543446, 1531.99822130574)
(84.33189414162649, 599662.479611736)
(-61.773195547875325, 235652.583151785)
(70.19651737074126, -345817.978897669)
(18.39024832457161, 6199.0182989207)
(-99.4677081521043, 984004.212040506)
(57.63247465051448, -191361.583946953)
(68.62596544703922, 323118.395275634)
(49.78054402717333, 123305.32876847)
(-24.0930341042649, 13958.3608013079)
(93.75577843219567, 824021.524765065)
(79.62003129242086, -504649.647549996)
(32.509776495644445, -34322.598384476)
(-0.9930127681864754, -0.540517904890456)
(82.76126653830434, -566774.189871195)
(92.18511836639324, -783294.302425734)
(4.377451737834387, -79.3516570131808)
(40.35927903448692, 65694.7183081863)
(100.03846146959651, 1001041.76363455)
(-30.369805738009997, 27976.73048386)
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:
$$x_{1} = -53.920980767268$$
$$x_{2} = -44.4991450273812$$
$$x_{3} = -63.3436910282739$$
$$x_{4} = -69.6258085806356$$
$$x_{5} = -66.4847245986491$$
$$x_{6} = 26.2320973823506$$
$$x_{7} = -19.3881624139967$$
$$x_{8} = -60.2027157509749$$
$$x_{9} = -3.82830914943635$$
$$x_{10} = -31.9393912700582$$
$$x_{11} = 7.45328197170462$$
$$x_{12} = -97.89703277248$$
$$x_{13} = 54.4916315442572$$
$$x_{14} = -9.99922859324132$$
$$x_{15} = -47.6396278004208$$
$$x_{16} = -6.89036083606886$$
$$x_{17} = 19.9578609060005$$
$$x_{18} = -91.6143727110982$$
$$x_{19} = -16.253975499135$$
$$x_{20} = -82.1905331189489$$
$$x_{21} = 35.6493413706884$$
$$x_{22} = 48.2102379751467$$
$$x_{23} = -85.3317899632627$$
$$x_{24} = 10.5660849493729$$
$$x_{25} = 98.4677847032998$$
$$x_{26} = 85.9025279122305$$
$$x_{27} = 63.9143816930814$$
$$x_{28} = 76.478825391736$$
$$x_{29} = 1.46875715449572$$
$$x_{30} = -88.4730706441605$$
$$x_{31} = -75.9081027685434$$
$$x_{32} = 13.6917269569451$$
$$x_{33} = 41.9293804173271$$
$$x_{34} = -25.6619341793609$$
$$x_{35} = -38.2187256644571$$
$$x_{36} = -41.3588305270381$$
$$x_{37} = 70.1965173707413$$
$$x_{38} = 57.6324746505145$$
$$x_{39} = 79.6200312924209$$
$$x_{40} = 32.5097764956444$$
$$x_{41} = -0.993012768186475$$
$$x_{42} = 82.7612665383043$$
$$x_{43} = 92.1851183663932$$
$$x_{44} = 4.37745173783439$$
Puntos máximos de la función:
$$x_{44} = -55.4913837591493$$
$$x_{44} = 12.1278990311653$$
$$x_{44} = -77.4786988837612$$
$$x_{44} = 65.4848967454959$$
$$x_{44} = -5.34908878227838$$
$$x_{44} = -74.3375151089096$$
$$x_{44} = 90.6144630226302$$
$$x_{44} = 34.0795123515579$$
$$x_{44} = -33.509089917422$$
$$x_{44} = -27.2310518364881$$
$$x_{44} = -42.9289644405571$$
$$x_{44} = 62.3438808011978$$
$$x_{44} = 24.6631136019729$$
$$x_{44} = 56.0620426091653$$
$$x_{44} = 46.6399648925705$$
$$x_{44} = -17.8207464039154$$
$$x_{44} = -96.3263613358694$$
$$x_{44} = 71.7670799851542$$
$$x_{44} = 87.4731675181051$$
$$x_{44} = -90.0437191441857$$
$$x_{44} = -8.44190646962111$$
$$x_{44} = -46.0693675258808$$
$$x_{44} = -39.7887487974318$$
$$x_{44} = -52.350601348512$$
$$x_{44} = 30.940147920832$$
$$x_{44} = 78.0494244526445$$
$$x_{44} = 21.5259340380784$$
$$x_{44} = -83.761158394026$$
$$x_{44} = 5.90751476216082$$
$$x_{44} = -68.0552607240211$$
$$x_{44} = 27.8012849208276$$
$$x_{44} = 43.4995318860771$$
$$x_{44} = -11.5600921825434$$
$$x_{44} = 84.3318941416265$$
$$x_{44} = -61.7731955478753$$
$$x_{44} = 18.3902483245716$$
$$x_{44} = -99.4677081521043$$
$$x_{44} = 68.6259654470392$$
$$x_{44} = 49.7805440271733$$
$$x_{44} = -24.0930341042649$$
$$x_{44} = 93.7557784321957$$
$$x_{44} = 40.3592790344869$$
$$x_{44} = 100.038461469597$$
$$x_{44} = -30.36980573801$$
Decrece en los intervalos
$$\left[98.4677847032998, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -97.89703277248\right]$$