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$$- \frac{x \cos{\left(x \right)}}{2} - \frac{\sin{\left(x \right)}}{2} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -64.4181717218392$$
$$x_{2} = -45.57503179559$$
$$x_{3} = 70.69997803861$$
$$x_{4} = -51.855560729152$$
$$x_{5} = -48.7152107175577$$
$$x_{6} = -7.97866571241324$$
$$x_{7} = 89.5465575382492$$
$$x_{8} = -42.4350618814099$$
$$x_{9} = 64.4181717218392$$
$$x_{10} = 36.1559664195367$$
$$x_{11} = -29.8785865061074$$
$$x_{12} = -98.9702722883957$$
$$x_{13} = 45.57503179559$$
$$x_{14} = -73.8409691490209$$
$$x_{15} = 98.9702722883957$$
$$x_{16} = 95.8290108090195$$
$$x_{17} = 14.2074367251912$$
$$x_{18} = 80.1230928148503$$
$$x_{19} = -20.469167402741$$
$$x_{20} = 73.8409691490209$$
$$x_{21} = -58.1366632448992$$
$$x_{22} = 4.91318043943488$$
$$x_{23} = -17.3363779239834$$
$$x_{24} = -61.2773745335697$$
$$x_{25} = 23.6042847729804$$
$$x_{26} = -39.295350981473$$
$$x_{27} = 58.1366632448992$$
$$x_{28} = -54.9960525574964$$
$$x_{29} = 83.2642147040886$$
$$x_{30} = 39.295350981473$$
$$x_{31} = 20.469167402741$$
$$x_{32} = 102.111554139654$$
$$x_{33} = 51.855560729152$$
$$x_{34} = 92.687771772017$$
$$x_{35} = 17.3363779239834$$
$$x_{36} = 0$$
$$x_{37} = -67.5590428388084$$
$$x_{38} = -11.085538406497$$
$$x_{39} = 7.97866571241324$$
$$x_{40} = -95.8290108090195$$
$$x_{41} = -14.2074367251912$$
$$x_{42} = 67.5590428388084$$
$$x_{43} = -70.69997803861$$
$$x_{44} = -23.6042847729804$$
$$x_{45} = 11.085538406497$$
$$x_{46} = -4.91318043943488$$
$$x_{47} = -76.9820093304187$$
$$x_{48} = 2.02875783811043$$
$$x_{49} = -26.7409160147873$$
$$x_{50} = 26.7409160147873$$
$$x_{51} = 54.9960525574964$$
$$x_{52} = -89.5465575382492$$
$$x_{53} = -36.1559664195367$$
$$x_{54} = -83.2642147040886$$
$$x_{55} = 86.4053708116885$$
$$x_{56} = 61.2773745335697$$
$$x_{57} = 76.9820093304187$$
$$x_{58} = -92.687771772017$$
$$x_{59} = 42.4350618814099$$
$$x_{60} = -86.4053708116885$$
$$x_{61} = 48.7152107175577$$
$$x_{62} = -33.0170010333572$$
$$x_{63} = 33.0170010333572$$
$$x_{64} = -80.1230928148503$$
$$x_{65} = -2.02875783811043$$
$$x_{66} = 29.8785865061074$$
Signos de extremos en los puntos:
(-64.41817172183916, -32.2052056696877)
(-45.57503179559002, -22.7820324180134)
(70.69997803861, -35.3464534807966)
(-51.85556072915197, -25.9229606251007)
(-48.715210717557724, 24.352475112684)
(-7.978665712413241, -3.95836368579389)
(89.54655753824919, -44.7704871864426)
(-42.43506188140989, 21.2116420386295)
(64.41817172183916, -32.2052056696877)
(36.15596641953672, 18.071072686121)
(-29.878586506107393, 14.9309330795934)
(-98.9702722883957, 49.4826103265593)
(45.57503179559002, -22.7820324180134)
(-73.8409691490209, 36.9170993857708)
(98.9702722883957, 49.4826103265593)
(95.82901080901948, -47.9118968042328)
(14.207436725191188, -7.08618705688714)
(80.12309281485025, 40.0584265728296)
(-20.46916740274095, -10.2223920291261)
(73.8409691490209, 36.9170993857708)
(-58.13666324489916, -29.0640323640429)
(4.913180439434884, 2.40723494485613)
(-17.33637792398336, 8.65380430392926)
(-61.277374533569656, 30.6346082722383)
(23.604284772980407, 11.7915653248167)
(-39.295350981472986, -19.6413165034459)
(58.13666324489916, -29.0640323640429)
(-54.99605255749639, 27.4934816248488)
(83.26421470408864, -41.6291051864766)
(39.295350981472986, -19.6413165034459)
(20.46916740274095, -10.2223920291261)
(102.11155413965392, -51.0533289431582)
(51.85556072915197, -25.9229606251007)
(92.687771772017, 46.3411888940296)
(17.33637792398336, 8.65380430392926)
(0, 0)
(-67.5590428388084, 33.7758215604863)
(-11.085538406497022, 5.520354007965)
(7.978665712413241, -3.95836368579389)
(-95.82901080901948, -47.9118968042328)
(-14.207436725191188, -7.08618705688714)
(67.5590428388084, 33.7758215604863)
(-70.69997803861, -35.3464534807966)
(-23.604284772980407, 11.7915653248167)
(11.085538406497022, 5.520354007965)
(-4.913180439434884, 2.40723494485613)
(-76.98200933041872, -38.4877575641319)
(2.028757838110434, -0.909852870579826)
(-26.74091601478731, -13.3611188323487)
(26.74091601478731, -13.3611188323487)
(54.99605255749639, 27.4934816248488)
(-89.54655753824919, -44.7704871864426)
(-36.15596641953672, 18.071072686121)
(-83.26421470408864, -41.6291051864766)
(86.40537081168854, 43.1997923578054)
(61.277374533569656, 30.6346082722383)
(76.98200933041872, -38.4877575641319)
(-92.687771772017, 46.3411888940296)
(42.43506188140989, 21.2116420386295)
(-86.40537081168854, 43.1997923578054)
(48.715210717557724, 24.352475112684)
(-33.017001033357246, -16.5009338654227)
(33.017001033357246, -16.5009338654227)
(-80.12309281485025, 40.0584265728296)
(-2.028757838110434, -0.909852870579826)
(29.878586506107393, 14.9309330795934)
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:
$$x_{1} = -64.4181717218392$$
$$x_{2} = -45.57503179559$$
$$x_{3} = 70.69997803861$$
$$x_{4} = -51.855560729152$$
$$x_{5} = -7.97866571241324$$
$$x_{6} = 89.5465575382492$$
$$x_{7} = 64.4181717218392$$
$$x_{8} = 45.57503179559$$
$$x_{9} = 95.8290108090195$$
$$x_{10} = 14.2074367251912$$
$$x_{11} = -20.469167402741$$
$$x_{12} = -58.1366632448992$$
$$x_{13} = -39.295350981473$$
$$x_{14} = 58.1366632448992$$
$$x_{15} = 83.2642147040886$$
$$x_{16} = 39.295350981473$$
$$x_{17} = 20.469167402741$$
$$x_{18} = 102.111554139654$$
$$x_{19} = 51.855560729152$$
$$x_{20} = 7.97866571241324$$
$$x_{21} = -95.8290108090195$$
$$x_{22} = -14.2074367251912$$
$$x_{23} = -70.69997803861$$
$$x_{24} = -76.9820093304187$$
$$x_{25} = 2.02875783811043$$
$$x_{26} = -26.7409160147873$$
$$x_{27} = 26.7409160147873$$
$$x_{28} = -89.5465575382492$$
$$x_{29} = -83.2642147040886$$
$$x_{30} = 76.9820093304187$$
$$x_{31} = -33.0170010333572$$
$$x_{32} = 33.0170010333572$$
$$x_{33} = -2.02875783811043$$
Puntos máximos de la función:
$$x_{33} = -48.7152107175577$$
$$x_{33} = -42.4350618814099$$
$$x_{33} = 36.1559664195367$$
$$x_{33} = -29.8785865061074$$
$$x_{33} = -98.9702722883957$$
$$x_{33} = -73.8409691490209$$
$$x_{33} = 98.9702722883957$$
$$x_{33} = 80.1230928148503$$
$$x_{33} = 73.8409691490209$$
$$x_{33} = 4.91318043943488$$
$$x_{33} = -17.3363779239834$$
$$x_{33} = -61.2773745335697$$
$$x_{33} = 23.6042847729804$$
$$x_{33} = -54.9960525574964$$
$$x_{33} = 92.687771772017$$
$$x_{33} = 17.3363779239834$$
$$x_{33} = 0$$
$$x_{33} = -67.5590428388084$$
$$x_{33} = -11.085538406497$$
$$x_{33} = 67.5590428388084$$
$$x_{33} = -23.6042847729804$$
$$x_{33} = 11.085538406497$$
$$x_{33} = -4.91318043943488$$
$$x_{33} = 54.9960525574964$$
$$x_{33} = -36.1559664195367$$
$$x_{33} = 86.4053708116885$$
$$x_{33} = 61.2773745335697$$
$$x_{33} = -92.687771772017$$
$$x_{33} = 42.4350618814099$$
$$x_{33} = -86.4053708116885$$
$$x_{33} = 48.7152107175577$$
$$x_{33} = -80.1230928148503$$
$$x_{33} = 29.8785865061074$$
Decrece en los intervalos
$$\left[102.111554139654, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -95.8290108090195\right]$$