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$$\frac{\left(- 2 x + \sin{\left(x \right)}\right) \left(x + \sin{\left(x \right)}\right)}{\left(x^{2} + \cos{\left(x \right)}\right)^{2}} + \frac{\cos{\left(x \right)} + 1}{x^{2} + \cos{\left(x \right)}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 43.9086304391986$$
$$x_{2} = 6.4735496375984$$
$$x_{3} = -37.6131292591587$$
$$x_{4} = -81.6965386967262$$
$$x_{5} = 100.543258652178$$
$$x_{6} = 25.0034968231157$$
$$x_{7} = -94.2608926838609$$
$$x_{8} = 75.3552861438656$$
$$x_{9} = 31.455217599475$$
$$x_{10} = -6.4735496375984$$
$$x_{11} = -62.8515189153841$$
$$x_{12} = 5.73303466805554$$
$$x_{13} = -75.3552861438656$$
$$x_{14} = -18.6767199929799$$
$$x_{15} = -87.9277947562266$$
$$x_{16} = 69.0681937171023$$
$$x_{17} = -69.0681937171023$$
$$x_{18} = -43.9086304391986$$
$$x_{19} = -50.2900599933538$$
$$x_{20} = 87.9277947562266$$
$$x_{21} = 31.3126714581803$$
$$x_{22} = -5.73303466805554$$
$$x_{23} = 50.2900599933538$$
$$x_{24} = -18.9148816474771$$
$$x_{25} = 113.108263605015$$
$$x_{26} = 37.6131292591587$$
$$x_{27} = 50.2010425988319$$
$$x_{28} = -56.5705169339472$$
$$x_{29} = 56.5705169339472$$
$$x_{30} = 56.4913991620551$$
$$x_{31} = -25.0034968231157$$
$$x_{32} = -87.9786437060689$$
$$x_{33} = -50.2010425988319$$
$$x_{34} = -25.1818171106898$$
$$x_{35} = -100.543258652178$$
$$x_{36} = -12.6638988770814$$
$$x_{37} = -31.455217599475$$
$$x_{38} = 75.4146136170676$$
$$x_{39} = 62.780318581017$$
$$x_{40} = -12.3048802608754$$
$$x_{41} = -44.0103811318779$$
$$x_{42} = 81.6965386967262$$
$$x_{43} = 12.3048802608754$$
$$x_{44} = -94.2134347195882$$
$$x_{45} = -904.775107583154$$
$$x_{46} = 12.6638988770814$$
$$x_{47} = -69.1329174891759$$
$$x_{48} = -81.6417767790886$$
$$x_{49} = 37.7318681711555$$
$$x_{50} = -100.498767620427$$
$$x_{51} = 94.2608926838609$$
$$x_{52} = 62.8515189153841$$
$$x_{53} = 44.0103811318779$$
$$x_{54} = -56.4913991620551$$
$$x_{55} = -31.3126714581803$$
$$x_{56} = 18.6767199929799$$
$$x_{57} = 25.1818171106898$$
$$x_{58} = 100.498767620427$$
$$x_{59} = -75.4146136170676$$
$$x_{60} = 87.9786437060689$$
$$x_{61} = 69.1329174891759$$
$$x_{62} = 81.6417767790886$$
$$x_{63} = -62.780318581017$$
$$x_{64} = 94.2134347195882$$
$$x_{65} = 18.9148816474771$$
$$x_{66} = -37.7318681711555$$
Signos de extremos en los puntos:
(43.908630439198596, 0.0227246361278357)
(6.473549637598396, 0.155349866598708)
(-37.613129259158654, -0.0265070930364385)
(-81.69653869672617, -0.0122408536123202)
(100.54325865217778, 0.0099461999375388)
(25.003496823115675, 0.0397252350960918)
(-94.26089268386087, -0.0106091353599299)
(75.35528614386557, 0.0132605768352458)
(31.45521759947502, 0.0317988150447749)
(-6.473549637598396, -0.155349866598708)
(-62.85151891538414, -0.0159114653095468)
(5.7330346680555415, 0.15451359971509)
(-75.35528614386557, -0.0132605768352458)
(-18.676719992979912, -0.0529001724657087)
(-87.9277947562266, -0.0113667400750096)
(69.06819371710233, 0.0144655990958247)
(-69.06819371710233, -0.0144655990958247)
(-43.908630439198596, -0.0227246361278357)
(-50.290059993353765, -0.0198865014262232)
(87.9277947562266, 0.0113667400750096)
(31.31267145818032, 0.0317985707321494)
(-5.7330346680555415, -0.15451359971509)
(50.290059993353765, 0.0198865014262232)
(-18.914881647477134, -0.0529033319326675)
(113.10826360501456, 0.00884125014988744)
(37.613129259158654, 0.0265070930364385)
(50.2010425988319, 0.0198864781703916)
(-56.57051693394717, -0.0176783566023099)
(56.57051693394717, 0.0176783566023099)
(56.4913991620551, 0.0176783437002106)
(-25.003496823115675, -0.0397252350960918)
(-87.9786437060689, -0.0113667414907799)
(-50.2010425988319, -0.0198864781703916)
(-25.18181711068984, -0.0397259819833676)
(-100.54325865217778, -0.0099461999375388)
(-12.663898877081408, -0.0790810287310917)
(-31.45521759947502, -0.0317988150447749)
(75.4146136170676, 0.0132605798957128)
(62.780318581016964, 0.0159114576923506)
(-12.304880260875393, -0.0790567615089993)
(-44.01038113187789, -0.0227246814855013)
(81.69653869672617, 0.0122408536123202)
(12.304880260875393, 0.0790567615089993)
(-94.21343471958815, -0.010609134357267)
(-904.775107583154, -0.00110524131023034)
(12.663898877081408, 0.0790810287310917)
(-69.1329174891759, -0.014465603824878)
(-81.64177677908862, -0.0122408515614264)
(37.73186817115554, 0.0265071911277167)
(-100.49876762042679, -0.00994619921144368)
(94.26089268386087, 0.0106091353599299)
(62.85151891538414, 0.0159114653095468)
(44.01038113187789, 0.0227246814855013)
(-56.4913991620551, -0.0176783437002106)
(-31.31267145818032, -0.0317985707321494)
(18.676719992979912, 0.0529001724657087)
(25.18181711068984, 0.0397259819833676)
(100.49876762042679, 0.00994619921144368)
(-75.4146136170676, -0.0132605798957128)
(87.9786437060689, 0.0113667414907799)
(69.1329174891759, 0.014465603824878)
(81.64177677908862, 0.0122408515614264)
(-62.780318581016964, -0.0159114576923506)
(94.21343471958815, 0.010609134357267)
(18.914881647477134, 0.0529033319326675)
(-37.73186817115554, -0.0265071911277167)
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:
$$x_{1} = 43.9086304391986$$
$$x_{2} = -81.6965386967262$$
$$x_{3} = 25.0034968231157$$
$$x_{4} = -94.2608926838609$$
$$x_{5} = -6.4735496375984$$
$$x_{6} = -62.8515189153841$$
$$x_{7} = 5.73303466805554$$
$$x_{8} = 69.0681937171023$$
$$x_{9} = -50.2900599933538$$
$$x_{10} = 31.3126714581803$$
$$x_{11} = -18.9148816474771$$
$$x_{12} = 37.6131292591587$$
$$x_{13} = 50.2010425988319$$
$$x_{14} = -56.5705169339472$$
$$x_{15} = 56.4913991620551$$
$$x_{16} = -25.1818171106898$$
$$x_{17} = -100.543258652178$$
$$x_{18} = -12.6638988770814$$
$$x_{19} = -31.455217599475$$
$$x_{20} = 62.780318581017$$
$$x_{21} = -44.0103811318779$$
$$x_{22} = 12.3048802608754$$
$$x_{23} = 18.6767199929799$$
$$x_{24} = -75.4146136170676$$
$$x_{25} = 81.6417767790886$$
$$x_{26} = 94.2134347195882$$
$$x_{27} = -37.7318681711555$$
Puntos máximos de la función:
$$x_{27} = 6.4735496375984$$
$$x_{27} = -37.6131292591587$$
$$x_{27} = 100.543258652178$$
$$x_{27} = 31.455217599475$$
$$x_{27} = -18.6767199929799$$
$$x_{27} = -69.0681937171023$$
$$x_{27} = -43.9086304391986$$
$$x_{27} = -5.73303466805554$$
$$x_{27} = 50.2900599933538$$
$$x_{27} = 113.108263605015$$
$$x_{27} = 56.5705169339472$$
$$x_{27} = -25.0034968231157$$
$$x_{27} = -50.2010425988319$$
$$x_{27} = 75.4146136170676$$
$$x_{27} = -12.3048802608754$$
$$x_{27} = 81.6965386967262$$
$$x_{27} = -94.2134347195882$$
$$x_{27} = 12.6638988770814$$
$$x_{27} = -81.6417767790886$$
$$x_{27} = 37.7318681711555$$
$$x_{27} = 94.2608926838609$$
$$x_{27} = 62.8515189153841$$
$$x_{27} = 44.0103811318779$$
$$x_{27} = -56.4913991620551$$
$$x_{27} = -31.3126714581803$$
$$x_{27} = 25.1818171106898$$
$$x_{27} = -62.780318581017$$
$$x_{27} = 18.9148816474771$$
Decrece en los intervalos
$$\left[94.2134347195882, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -100.543258652178\right]$$