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$$\frac{x \sin{\left(2 x \right)}}{2} - \frac{\cos{\left(2 x \right)}}{4} + \frac{1}{4} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -14.1724320747999$$
$$x_{2} = 51.8459224452234$$
$$x_{3} = -61.2692172687226$$
$$x_{4} = 67.5516436614121$$
$$x_{5} = 73.8341991854591$$
$$x_{6} = -36.1421488970061$$
$$x_{7} = -105.248104538899$$
$$x_{8} = 14.1724320747999$$
$$x_{9} = -89.5409746049841$$
$$x_{10} = -53.4070751110265$$
$$x_{11} = -80.1168534696549$$
$$x_{12} = -7.91705268466621$$
$$x_{13} = -9.42477796076938$$
$$x_{14} = 28.2743338823081$$
$$x_{15} = 50.2654824574367$$
$$x_{16} = -97.3893722612836$$
$$x_{17} = -58.1280655761511$$
$$x_{18} = 70.692907433161$$
$$x_{19} = -84.8230016469244$$
$$x_{20} = 36.1421488970061$$
$$x_{21} = 86.3995849739529$$
$$x_{22} = 92.682377997352$$
$$x_{23} = 34.5575191894877$$
$$x_{24} = 20.4448034666183$$
$$x_{25} = 1.83659720315213$$
$$x_{26} = 65.9734457253857$$
$$x_{27} = 0$$
$$x_{28} = -67.5516436614121$$
$$x_{29} = 58.1280655761511$$
$$x_{30} = 3.14159265358979$$
$$x_{31} = 78.5398163397448$$
$$x_{32} = -1.83659720315213$$
$$x_{33} = -20.4448034666183$$
$$x_{34} = 59.6902604182061$$
$$x_{35} = -42.4232862577008$$
$$x_{36} = 80.1168534696549$$
$$x_{37} = 100.530964914873$$
$$x_{38} = -72.2566310325652$$
$$x_{39} = 278.032748190065$$
$$x_{40} = 21.9911485751286$$
$$x_{41} = -23.5831433102848$$
$$x_{42} = -37.6991118430775$$
$$x_{43} = -81.6814089933346$$
$$x_{44} = -21.9911485751286$$
$$x_{45} = 12.5663706143592$$
$$x_{46} = -87.9645943005142$$
$$x_{47} = -51.8459224452234$$
$$x_{48} = -94.2477796076938$$
$$x_{49} = -29.861872403816$$
$$x_{50} = 26.7222463741877$$
$$x_{51} = 15.707963267949$$
$$x_{52} = -86.3995849739529$$
$$x_{53} = -43.9822971502571$$
$$x_{54} = 89.5409746049841$$
$$x_{55} = -6.28318530717959$$
$$x_{56} = -95.8237937978449$$
$$x_{57} = -4.81584231784594$$
$$x_{58} = 95.8237937978449$$
$$x_{59} = -28.2743338823081$$
$$x_{60} = 81.6814089933346$$
$$x_{61} = -75.398223686155$$
$$x_{62} = 29.861872403816$$
$$x_{63} = 94.2477796076938$$
$$x_{64} = -39.2826357527234$$
$$x_{65} = -59.6902604182061$$
$$x_{66} = 87.9645943005142$$
$$x_{67} = -45.5640665961997$$
$$x_{68} = -1.83659720315213$$
$$x_{69} = -64.410411962776$$
$$x_{70} = 64.410411962776$$
$$x_{71} = -15.707963267949$$
$$x_{72} = 23.5831433102848$$
$$x_{73} = 42.4232862577008$$
$$x_{74} = -73.8341991854591$$
$$x_{75} = 6.28318530717959$$
$$x_{76} = -50.2654824574367$$
$$x_{77} = 37.6991118430775$$
$$x_{78} = -17.3076405374146$$
$$x_{79} = 43.9822971502571$$
$$x_{80} = 56.5486677646163$$
$$x_{81} = -65.9734457253857$$
$$x_{82} = -83.2582106616487$$
$$x_{83} = 25.1327412287183$$
$$x_{84} = 48.7049516666752$$
$$x_{85} = 7.91705268466621$$
$$x_{86} = -31.4159265358979$$
$$x_{87} = 45.5640665961997$$
$$x_{88} = 72.2566310325652$$
Signos de extremos en los puntos:
(-14.172432074799941, -7.07740706163164)
(51.84592244522343, 25.920550456838)
(-61.269217268722585, -30.6325685940035)
(67.5516436614121, 33.7739714959788)
(73.83419918545908, 36.915406687961)
(-36.142148897006074, -18.0676165445035)
(-105.24810453889911, -52.6228646264085)
(14.172432074799941, 7.07740706163164)
(-89.54097460498406, -44.7690913370919)
(-53.40707511102649, 0)
(-80.11685346965491, -40.0568665745591)
(-7.917052684666207, -3.94280036206377)
(-9.42477796076938, 0)
(28.274333882308138, 0)
(50.26548245743669, 0)
(-97.3893722612836, 0)
(-58.12806557615112, -29.0618825229533)
(70.692907433161, 35.3446855936993)
(-84.82300164692441, 0)
(36.142148897006074, 18.0676165445035)
(86.3995849739529, 43.1983457692183)
(92.68237799735202, 46.3398403457296)
(34.55751918948773, 0)
(20.4448034666183, 10.216291364856)
(1.8365972031521258, 0.854934264616044)
(65.97344572538566, 0)
(0, 0)
(-67.5516436614121, -33.7739714959788)
(58.12806557615112, 29.0618825229533)
(3.141592653589793, 0)
(78.53981633974483, 0)
(-1.8365972031521258, -0.854934264616044)
(-20.4448034666183, -10.216291364856)
(59.69026041820607, 0)
(-42.423286257700816, -21.208697043109)
(80.11685346965491, 40.0568665745591)
(100.53096491487338, 0)
(-72.25663103256524, 0)
(278.0327481900649, 139.01592450916)
(21.991148575128552, 0)
(-23.583143310284843, -11.7862736405731)
(-37.69911184307752, 0)
(-81.68140899333463, 0)
(-21.991148575128552, 0)
(12.566370614359172, 0)
(-87.96459430051421, 0)
(-51.84592244522343, -25.920550456838)
(-94.2477796076938, 0)
(-29.861872403816044, -14.9267514353285)
(26.72224637418772, 13.3564470737586)
(15.707963267948966, 0)
(-86.3995849739529, -43.1983457692183)
(-43.982297150257104, 0)
(89.54097460498406, 44.7690913370919)
(-6.283185307179586, 0)
(-95.82379379784489, -47.9105924567603)
(-4.815842317845935, -2.38224196645101)
(95.82379379784489, 47.9105924567603)
(-28.274333882308138, 0)
(81.68140899333463, 0)
(-75.39822368615503, 0)
(29.861872403816044, 14.9267514353285)
(94.2477796076938, 0)
(-39.282635752723394, -19.6381363242642)
(-59.69026041820607, 0)
(87.96459430051421, 0)
(-45.56406659619972, -22.7792902385186)
(-1.8365972031521256, -0.854934264616044)
(-64.41041196277601, -32.2032654182994)
(64.41041196277601, 32.2032654182994)
(-15.707963267948966, 0)
(23.583143310284843, 11.7862736405731)
(42.423286257700816, 21.208697043109)
(-73.83419918545908, -36.915406687961)
(6.283185307179586, 0)
(-50.26548245743669, 0)
(37.69911184307752, 0)
(-17.307640537414635, -8.64660404734487)
(43.982297150257104, 0)
(56.548667764616276, 0)
(-65.97344572538566, 0)
(-83.25821066164869, -41.6276040315405)
(25.132741228718345, 0)
(48.70495166667517, 24.3499096296246)
(7.917052684666207, 3.94280036206377)
(-31.41592653589793, 0)
(45.56406659619972, 22.7792902385186)
(72.25663103256524, 0)
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:
$$x_{1} = -14.1724320747999$$
$$x_{2} = -61.2692172687226$$
$$x_{3} = -36.1421488970061$$
$$x_{4} = -105.248104538899$$
$$x_{5} = -89.5409746049841$$
$$x_{6} = -80.1168534696549$$
$$x_{7} = -7.91705268466621$$
$$x_{8} = 28.2743338823081$$
$$x_{9} = 50.2654824574367$$
$$x_{10} = -58.1280655761511$$
$$x_{11} = 34.5575191894877$$
$$x_{12} = 65.9734457253857$$
$$x_{13} = -67.5516436614121$$
$$x_{14} = 3.14159265358979$$
$$x_{15} = 78.5398163397448$$
$$x_{16} = -1.83659720315213$$
$$x_{17} = -20.4448034666183$$
$$x_{18} = 59.6902604182061$$
$$x_{19} = -42.4232862577008$$
$$x_{20} = 100.530964914873$$
$$x_{21} = 21.9911485751286$$
$$x_{22} = -23.5831433102848$$
$$x_{23} = 12.5663706143592$$
$$x_{24} = -51.8459224452234$$
$$x_{25} = -29.861872403816$$
$$x_{26} = 15.707963267949$$
$$x_{27} = -86.3995849739529$$
$$x_{28} = -95.8237937978449$$
$$x_{29} = -4.81584231784594$$
$$x_{30} = 81.6814089933346$$
$$x_{31} = 94.2477796076938$$
$$x_{32} = -39.2826357527234$$
$$x_{33} = 87.9645943005142$$
$$x_{34} = -45.5640665961997$$
$$x_{35} = -1.83659720315213$$
$$x_{36} = -64.410411962776$$
$$x_{37} = -73.8341991854591$$
$$x_{38} = 6.28318530717959$$
$$x_{39} = 37.6991118430775$$
$$x_{40} = -17.3076405374146$$
$$x_{41} = 43.9822971502571$$
$$x_{42} = 56.5486677646163$$
$$x_{43} = -83.2582106616487$$
$$x_{44} = 25.1327412287183$$
$$x_{45} = 72.2566310325652$$
Puntos máximos de la función:
$$x_{45} = 51.8459224452234$$
$$x_{45} = 67.5516436614121$$
$$x_{45} = 73.8341991854591$$
$$x_{45} = 14.1724320747999$$
$$x_{45} = -53.4070751110265$$
$$x_{45} = -9.42477796076938$$
$$x_{45} = -97.3893722612836$$
$$x_{45} = 70.692907433161$$
$$x_{45} = -84.8230016469244$$
$$x_{45} = 36.1421488970061$$
$$x_{45} = 86.3995849739529$$
$$x_{45} = 92.682377997352$$
$$x_{45} = 20.4448034666183$$
$$x_{45} = 1.83659720315213$$
$$x_{45} = 58.1280655761511$$
$$x_{45} = 80.1168534696549$$
$$x_{45} = -72.2566310325652$$
$$x_{45} = 278.032748190065$$
$$x_{45} = -37.6991118430775$$
$$x_{45} = -81.6814089933346$$
$$x_{45} = -21.9911485751286$$
$$x_{45} = -87.9645943005142$$
$$x_{45} = -94.2477796076938$$
$$x_{45} = 26.7222463741877$$
$$x_{45} = -43.9822971502571$$
$$x_{45} = 89.5409746049841$$
$$x_{45} = -6.28318530717959$$
$$x_{45} = 95.8237937978449$$
$$x_{45} = -28.2743338823081$$
$$x_{45} = -75.398223686155$$
$$x_{45} = 29.861872403816$$
$$x_{45} = -59.6902604182061$$
$$x_{45} = 64.410411962776$$
$$x_{45} = -15.707963267949$$
$$x_{45} = 23.5831433102848$$
$$x_{45} = 42.4232862577008$$
$$x_{45} = -50.2654824574367$$
$$x_{45} = -65.9734457253857$$
$$x_{45} = 48.7049516666752$$
$$x_{45} = 7.91705268466621$$
$$x_{45} = -31.4159265358979$$
$$x_{45} = 45.5640665961997$$
Decrece en los intervalos
$$\left[100.530964914873, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -105.248104538899\right]$$