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$$\frac{x \cos{\left(x \right)}}{\sqrt{x^{2} + 1}} - \sqrt{x^{2} + 1} \sin{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 28.3095989432302$$
$$x_{2} = 9.52821549266106$$
$$x_{3} = -65.9885952207735$$
$$x_{4} = 81.6936474022746$$
$$x_{5} = 100.540909803188$$
$$x_{6} = 59.7070026111652$$
$$x_{7} = -6.43379886230022$$
$$x_{8} = -18.9022631237701$$
$$x_{9} = 18.9022631237701$$
$$x_{10} = -53.4257839266448$$
$$x_{11} = -44.0050062036989$$
$$x_{12} = -22.0364038524226$$
$$x_{13} = -25.1723839280852$$
$$x_{14} = 72.2704644126133$$
$$x_{15} = 56.5663387600798$$
$$x_{16} = 44.0050062036989$$
$$x_{17} = 50.2853584825179$$
$$x_{18} = 12.6448017404916$$
$$x_{19} = 94.2583871513449$$
$$x_{20} = -34.5864001053667$$
$$x_{21} = -81.6936474022746$$
$$x_{22} = 87.9759590844472$$
$$x_{23} = 84.8347870808599$$
$$x_{24} = 34.5864001053667$$
$$x_{25} = 53.4257839266448$$
$$x_{26} = 47.1450882065006$$
$$x_{27} = -12.6448017404916$$
$$x_{28} = 22.0364038524226$$
$$x_{29} = -94.2583871513449$$
$$x_{30} = -28.3095989432302$$
$$x_{31} = -75.4114811582976$$
$$x_{32} = 91.1171600730396$$
$$x_{33} = 0$$
$$x_{34} = -3.40560803085714$$
$$x_{35} = 40.8651557032987$$
$$x_{36} = 6.43379886230022$$
$$x_{37} = 25.1723839280852$$
$$x_{38} = 31.4476825808931$$
$$x_{39} = -37.7255942421573$$
$$x_{40} = -69.129499948813$$
$$x_{41} = -40.8651557032987$$
$$x_{42} = 37.7255942421573$$
$$x_{43} = -59.7070026111652$$
$$x_{44} = -15.7710329877954$$
$$x_{45} = -87.9759590844472$$
$$x_{46} = -78.5525439221505$$
$$x_{47} = -56.5663387600798$$
$$x_{48} = 65.9885952207735$$
$$x_{49} = -91.1171600730396$$
$$x_{50} = 8.05441369435448 \cdot 10^{-5}$$
$$x_{51} = -50.2853584825179$$
$$x_{52} = 62.8477591691304$$
$$x_{53} = 97.399637797165$$
$$x_{54} = -62.8477591691304$$
$$x_{55} = 75.4114811582976$$
$$x_{56} = -84.8347870808599$$
$$x_{57} = -100.540909803188$$
$$x_{58} = 3.40560803085714$$
$$x_{59} = -97.399637797165$$
$$x_{60} = -31.4476825808931$$
$$x_{61} = -47.1450882065006$$
$$x_{62} = 69.129499948813$$
$$x_{63} = 15.7710329877954$$
$$x_{64} = -72.2704644126133$$
$$x_{65} = -9.52821549266106$$
$$x_{66} = 78.5525439221505$$
Signos de extremos en los puntos:
(28.309598943230245, -28.3096428818132)
(9.528215492661063, -9.52934049888207)
(-65.98859522077348, -65.9885986988896)
(81.6936474022746, 81.693649235739)
(100.54090980318757, 100.540910786891)
(59.70700261116519, -59.7070073059937)
(-6.43379886230022, 6.4373394000213)
(-18.90226312377012, 18.9024101617613)
(18.90226312377012, 18.9024101617613)
(-53.42578392664482, -53.4257904785418)
(-44.00500620369887, 44.0050179238547)
(-22.036403852422588, -22.0364968233701)
(-25.17238392808519, 25.1724463758063)
(72.27046441261326, -72.2704670605624)
(56.566338760079816, 56.5663442806838)
(44.00500620369887, 44.0050179238547)
(50.28535848251788, 50.2853663393263)
(12.644801740491571, 12.6452887324562)
(94.25838715134489, 94.258388345107)
(-34.586400105366685, -34.586424225358)
(-81.6936474022746, 81.693649235739)
(87.97595908444723, 87.975960552588)
(84.83478708085987, -84.834788718156)
(34.586400105366685, -34.586424225358)
(53.42578392664482, -53.4257904785418)
(47.145088206500624, -47.145097738904)
(-12.644801740491571, 12.6452887324562)
(22.036403852422588, -22.0364968233701)
(-94.25838715134489, 94.258388345107)
(-28.309598943230245, -28.3096428818132)
(-75.41148115829758, 75.411483489053)
(91.1171600730396, -91.1171613945443)
(0, 1)
(-3.405608030857143, -3.42640288380261)
(40.86515570329874, -40.8651703348649)
(6.43379886230022, 6.4373394000213)
(25.17238392808519, 25.1724463758063)
(31.44768258089308, 31.4477146537371)
(-37.72559424215732, 37.7256128343013)
(-69.129499948813, 69.1295029742117)
(-40.86515570329874, -40.8651703348649)
(37.72559424215732, 37.7256128343013)
(-59.70700261116519, -59.7070073059937)
(-15.771032987795381, -15.771285379125)
(-87.97595908444723, 87.975960552588)
(-78.55254392215049, -78.55254598441)
(-56.566338760079816, 56.5663442806838)
(65.98859522077348, -65.9885986988896)
(-91.1171600730396, -91.1171613945443)
(8.05441369435448e-05, 1)
(-50.28535848251788, 50.2853663393263)
(62.847759169130406, 62.8477631949639)
(97.39963779716497, -97.3996388791308)
(-62.847759169130406, 62.8477631949639)
(75.41148115829758, 75.411483489053)
(-84.83478708085987, -84.834788718156)
(-100.54090980318757, 100.540910786891)
(3.405608030857143, -3.42640288380261)
(-97.39963779716497, -97.3996388791308)
(-31.44768258089308, 31.4477146537371)
(-47.145088206500624, -47.145097738904)
(69.129499948813, 69.1295029742117)
(15.771032987795381, -15.771285379125)
(-72.27046441261326, -72.2704670605624)
(-9.528215492661063, -9.52934049888207)
(78.55254392215049, -78.55254598441)
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:
$$x_{1} = 28.3095989432302$$
$$x_{2} = 9.52821549266106$$
$$x_{3} = -65.9885952207735$$
$$x_{4} = 59.7070026111652$$
$$x_{5} = -53.4257839266448$$
$$x_{6} = -22.0364038524226$$
$$x_{7} = 72.2704644126133$$
$$x_{8} = -34.5864001053667$$
$$x_{9} = 84.8347870808599$$
$$x_{10} = 34.5864001053667$$
$$x_{11} = 53.4257839266448$$
$$x_{12} = 47.1450882065006$$
$$x_{13} = 22.0364038524226$$
$$x_{14} = -28.3095989432302$$
$$x_{15} = 91.1171600730396$$
$$x_{16} = -3.40560803085714$$
$$x_{17} = 40.8651557032987$$
$$x_{18} = -40.8651557032987$$
$$x_{19} = -59.7070026111652$$
$$x_{20} = -15.7710329877954$$
$$x_{21} = -78.5525439221505$$
$$x_{22} = 65.9885952207735$$
$$x_{23} = -91.1171600730396$$
$$x_{24} = 8.05441369435448 \cdot 10^{-5}$$
$$x_{25} = 97.399637797165$$
$$x_{26} = -84.8347870808599$$
$$x_{27} = 3.40560803085714$$
$$x_{28} = -97.399637797165$$
$$x_{29} = -47.1450882065006$$
$$x_{30} = 15.7710329877954$$
$$x_{31} = -72.2704644126133$$
$$x_{32} = -9.52821549266106$$
$$x_{33} = 78.5525439221505$$
Puntos máximos de la función:
$$x_{33} = 81.6936474022746$$
$$x_{33} = 100.540909803188$$
$$x_{33} = -6.43379886230022$$
$$x_{33} = -18.9022631237701$$
$$x_{33} = 18.9022631237701$$
$$x_{33} = -44.0050062036989$$
$$x_{33} = -25.1723839280852$$
$$x_{33} = 56.5663387600798$$
$$x_{33} = 44.0050062036989$$
$$x_{33} = 50.2853584825179$$
$$x_{33} = 12.6448017404916$$
$$x_{33} = 94.2583871513449$$
$$x_{33} = -81.6936474022746$$
$$x_{33} = 87.9759590844472$$
$$x_{33} = -12.6448017404916$$
$$x_{33} = -94.2583871513449$$
$$x_{33} = -75.4114811582976$$
$$x_{33} = 6.43379886230022$$
$$x_{33} = 25.1723839280852$$
$$x_{33} = 31.4476825808931$$
$$x_{33} = -37.7255942421573$$
$$x_{33} = -69.129499948813$$
$$x_{33} = 37.7255942421573$$
$$x_{33} = -87.9759590844472$$
$$x_{33} = -56.5663387600798$$
$$x_{33} = -50.2853584825179$$
$$x_{33} = 62.8477591691304$$
$$x_{33} = -62.8477591691304$$
$$x_{33} = 75.4114811582976$$
$$x_{33} = -100.540909803188$$
$$x_{33} = -31.4476825808931$$
$$x_{33} = 69.129499948813$$
Decrece en los intervalos
$$\left[97.399637797165, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -97.399637797165\right]$$