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$$\frac{3 \cos{\left(\frac{3 x}{2} \right)}}{2} - \frac{4 \cot^{2}{\left(\frac{4 x}{3} \right)}}{3} - \frac{4}{3} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 293.484286571338$$
$$x_{2} = 100.237393538035$$
$$x_{3} = 83.5068318594376$$
$$x_{4} = -83.5068318594376$$
$$x_{5} = 12.7481910272038$$
$$x_{6} = 8.10860817328255$$
$$x_{7} = 62.6500326589512$$
$$x_{8} = -1063.68373977945$$
$$x_{9} = -50.5590538342749$$
$$x_{10} = 62.5382816949577$$
$$x_{11} = -352.151948578895$$
$$x_{12} = 12.8599419911974$$
$$x_{13} = 50.4473028702814$$
$$x_{14} = 46.1859120311904$$
$$x_{15} = -83.8850238742679$$
$$x_{16} = -88.1464147133589$$
$$x_{17} = 158.905055545593$$
$$x_{18} = 88.1464147133589$$
$$x_{19} = 83.8850238742679$$
$$x_{20} = -24.9509208158737$$
$$x_{21} = 66.9114234980422$$
$$x_{22} = 67.2896155128725$$
$$x_{23} = 252533.602045749$$
$$x_{24} = 24.8391698518802$$
$$x_{25} = -104.98872735595$$
$$x_{26} = -88.2581656773524$$
$$x_{27} = -24.8391698518802$$
$$x_{28} = -4645.47755688665$$
$$x_{29} = -67.2896155128725$$
$$x_{30} = -137.936505381113$$
$$x_{31} = -29.590503669795$$
$$x_{32} = -100.237393538035$$
$$x_{33} = -12.8599419911974$$
$$x_{34} = 24.9509208158737$$
$$x_{35} = 50.5590538342749$$
$$x_{36} = 29.2123116549653$$
$$x_{37} = -8.10860817328255$$
$$x_{38} = -50.4473028702814$$
$$x_{39} = 29.590503669795$$
$$x_{40} = -12.7481910272038$$
$$x_{41} = -62.5382816949577$$
$$x_{42} = -4272.74782929496$$
$$x_{43} = -45.8077200163601$$
$$x_{44} = 88.2581656773524$$
Signos de extremos en los puntos:
(293.4842865713376, 0.206396274705096)
(100.23739353803519, -0.559207809241328)
(83.5068318594376, -0.206396274705078)
(-83.5068318594376, 0.206396274705078)
(12.748191027203838, 0.558185315871553)
(8.108608173282551, -0.206396274705081)
(62.650032658951204, -0.558185315871546)
(-1063.6837397794532, 0.206396274705187)
(-50.55905383427488, -0.559207809241328)
(62.538281694957675, -0.559207809241335)
(-352.15194857889503, -0.559207809241405)
(12.85994199119736, 0.559207809241335)
(50.447302870281355, 0.558185315871553)
(46.185912031190405, -0.168468423313238)
(-83.88502387426792, 0.168468423313237)
(-88.14641471335888, -0.558185315871558)
(158.90505554559303, -0.206396274705073)
(88.14641471335888, 0.558185315871558)
(83.88502387426792, -0.168468423313237)
(-24.950920815873683, 0.558185315871553)
(66.91142349804215, 0.168468423313237)
(67.28961551287249, 0.206396274705076)
(252533.60204574908, -0.55818531585053)
(24.839169851880158, -0.559207809241335)
(-104.98872735595, -0.206396274705083)
(-88.2581656773524, -0.559207809241335)
(-24.839169851880158, 0.559207809241335)
(-4645.477556886648, 0.168468423312564)
(-67.28961551287249, -0.206396274705076)
(-137.9365053811127, 0.559207809241347)
(-29.590503669794966, -0.206396274705084)
(-100.23739353803519, 0.559207809241328)
(-12.85994199119736, -0.559207809241335)
(24.950920815873683, -0.558185315871553)
(50.55905383427488, 0.559207809241328)
(29.2123116549653, 0.16846842331324)
(-8.108608173282551, 0.206396274705081)
(-50.447302870281355, -0.558185315871553)
(29.590503669794966, 0.206396274705084)
(-12.748191027203838, -0.558185315871553)
(-62.538281694957675, 0.559207809241335)
(-4272.747829294964, -0.558185315872208)
(-45.80772001636007, 0.206396274705077)
(88.2581656773524, 0.559207809241335)
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:
$$x_{1} = 100.237393538035$$
$$x_{2} = 83.5068318594376$$
$$x_{3} = 12.7481910272038$$
$$x_{4} = 8.10860817328255$$
$$x_{5} = -50.5590538342749$$
$$x_{6} = 62.5382816949577$$
$$x_{7} = -352.151948578895$$
$$x_{8} = 50.4473028702814$$
$$x_{9} = -83.8850238742679$$
$$x_{10} = 158.905055545593$$
$$x_{11} = 88.1464147133589$$
$$x_{12} = -24.9509208158737$$
$$x_{13} = 66.9114234980422$$
$$x_{14} = 24.8391698518802$$
$$x_{15} = -104.98872735595$$
$$x_{16} = -88.2581656773524$$
$$x_{17} = -4645.47755688665$$
$$x_{18} = -67.2896155128725$$
$$x_{19} = -29.590503669795$$
$$x_{20} = -12.8599419911974$$
$$x_{21} = 29.2123116549653$$
Puntos máximos de la función:
$$x_{21} = 293.484286571338$$
$$x_{21} = -83.5068318594376$$
$$x_{21} = 62.6500326589512$$
$$x_{21} = -1063.68373977945$$
$$x_{21} = 12.8599419911974$$
$$x_{21} = 46.1859120311904$$
$$x_{21} = -88.1464147133589$$
$$x_{21} = 83.8850238742679$$
$$x_{21} = 67.2896155128725$$
$$x_{21} = -24.8391698518802$$
$$x_{21} = -137.936505381113$$
$$x_{21} = -100.237393538035$$
$$x_{21} = 24.9509208158737$$
$$x_{21} = 50.5590538342749$$
$$x_{21} = -8.10860817328255$$
$$x_{21} = -50.4473028702814$$
$$x_{21} = 29.590503669795$$
$$x_{21} = -12.7481910272038$$
$$x_{21} = -62.5382816949577$$
$$x_{21} = -4272.74782929496$$
$$x_{21} = -45.8077200163601$$
$$x_{21} = 88.2581656773524$$
Decrece en los intervalos
$$\left[158.905055545593, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -4645.47755688665\right]$$