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$$- \frac{\left(9 x + 3\right) e^{- x}}{2} + \frac{\cos{\left(x \right)}}{2} + \frac{9 e^{- x}}{2} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 73.8274273593601$$
$$x_{2} = 42.4115008234622$$
$$x_{3} = 7.82830652008065$$
$$x_{4} = 20.4203520076512$$
$$x_{5} = 58.1194640914112$$
$$x_{6} = 17.2787642785079$$
$$x_{7} = 70.6858347057703$$
$$x_{8} = 54.9778714378214$$
$$x_{9} = 36.1283155162827$$
$$x_{10} = 4.98207265104549$$
$$x_{11} = 92.6769832808989$$
$$x_{12} = 39.2699081698724$$
$$x_{13} = 14.1370790453827$$
$$x_{14} = 98.9601685880785$$
$$x_{15} = 86.3937979737193$$
$$x_{16} = 51.8362787842316$$
$$x_{17} = 80.1106126665397$$
$$x_{18} = 95.8185759344887$$
$$x_{19} = 45.553093477052$$
$$x_{20} = 32.9867228626915$$
$$x_{21} = 48.6946861306418$$
$$x_{22} = 76.9690200129499$$
$$x_{23} = 26.7035375549208$$
$$x_{24} = 0.83848399072257$$
$$x_{25} = 10.9971315757601$$
$$x_{26} = 61.261056745001$$
$$x_{27} = 64.4026493985908$$
$$x_{28} = 89.5353906273091$$
$$x_{29} = 67.5442420521806$$
$$x_{30} = 83.2522053201295$$
$$x_{31} = 29.8451302091317$$
$$x_{32} = 23.5619449139784$$
Signos de extremos en los puntos:
(73.82742735936014, -0.5)
(42.41150082346221, -0.5)
(7.82830652008065, 0.514463700130996)
(20.420352007651193, 0.500000126433307)
(58.119464091411174, 0.5)
(17.278764278507854, -0.499997517138029)
(70.68583470577035, 0.5)
(54.977871437821385, -0.5)
(36.12831551628269, -0.499999999999967)
(4.982072651045488, -0.317845100385589)
(92.6769832808989, -0.5)
(39.269908169872416, 0.500000000000002)
(14.137079045382743, 0.500047208503574)
(98.96016858807849, -0.5)
(86.39379797371932, -0.5)
(51.83627878423159, 0.5)
(80.11061266653972, -0.5)
(95.81857593448869, 0.5)
(45.553093477052, 0.5)
(32.98672286269146, 0.500000000000708)
(48.6946861306418, -0.5)
(76.96902001294994, 0.5)
(26.703537554920818, 0.500000000307588)
(0.83848399072257, 2.65175540075837)
(10.997131575760095, -0.499145376383222)
(61.26105674500097, -0.5)
(64.40264939859077, 0.5)
(89.53539062730911, 0.5)
(67.54424205218055, -0.5)
(83.25220532012952, 0.5)
(29.845130209131725, -0.499999999985163)
(23.561944913978408, -0.499999993709257)
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:
$$x_{1} = 73.8274273593601$$
$$x_{2} = 42.4115008234622$$
$$x_{3} = 17.2787642785079$$
$$x_{4} = 54.9778714378214$$
$$x_{5} = 36.1283155162827$$
$$x_{6} = 4.98207265104549$$
$$x_{7} = 92.6769832808989$$
$$x_{8} = 98.9601685880785$$
$$x_{9} = 86.3937979737193$$
$$x_{10} = 80.1106126665397$$
$$x_{11} = 48.6946861306418$$
$$x_{12} = 10.9971315757601$$
$$x_{13} = 61.261056745001$$
$$x_{14} = 67.5442420521806$$
$$x_{15} = 29.8451302091317$$
$$x_{16} = 23.5619449139784$$
Puntos máximos de la función:
$$x_{16} = 7.82830652008065$$
$$x_{16} = 20.4203520076512$$
$$x_{16} = 58.1194640914112$$
$$x_{16} = 70.6858347057703$$
$$x_{16} = 39.2699081698724$$
$$x_{16} = 14.1370790453827$$
$$x_{16} = 51.8362787842316$$
$$x_{16} = 95.8185759344887$$
$$x_{16} = 45.553093477052$$
$$x_{16} = 32.9867228626915$$
$$x_{16} = 76.9690200129499$$
$$x_{16} = 26.7035375549208$$
$$x_{16} = 0.83848399072257$$
$$x_{16} = 64.4026493985908$$
$$x_{16} = 89.5353906273091$$
$$x_{16} = 83.2522053201295$$
Decrece en los intervalos
$$\left[98.9601685880785, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, 4.98207265104549\right]$$