In order to find the extrema, we need to solve the equation
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(the derivative equals zero),
and the roots of this equation are the extrema of this function:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative$$- \frac{\sin{\left(x \right)}}{x} - \frac{2 \cos{\left(x \right)}}{x^{2}} + \frac{2 \sin{\left(x \right)}}{x^{3}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 9.20584014293667$$
$$x_{2} = -25.052825280993$$
$$x_{3} = -62.8000005565198$$
$$x_{4} = 87.9418500396598$$
$$x_{5} = -100.511065295271$$
$$x_{6} = 2.0815759778181$$
$$x_{7} = -18.7426455847748$$
$$x_{8} = 28.2033610039524$$
$$x_{9} = -2.0815759778181$$
$$x_{10} = 18.7426455847748$$
$$x_{11} = 43.9367614714198$$
$$x_{12} = 72.2289377620154$$
$$x_{13} = -72.2289377620154$$
$$x_{14} = 34.499514921367$$
$$x_{15} = -40.7916552312719$$
$$x_{16} = 25.052825280993$$
$$x_{17} = -342.42775856009$$
$$x_{18} = -31.3520917265645$$
$$x_{19} = 15.5792364103872$$
$$x_{20} = 94.2265525745684$$
$$x_{21} = -65.9431119046552$$
$$x_{22} = -21.8996964794928$$
$$x_{23} = 47.0813974121542$$
$$x_{24} = -81.6569138240367$$
$$x_{25} = -75.3716854092873$$
$$x_{26} = 50.2256516491831$$
$$x_{27} = 12.404445021902$$
$$x_{28} = -37.6459603230864$$
$$x_{29} = -43.9367614714198$$
$$x_{30} = 53.3695918204908$$
$$x_{31} = -94.2265525745684$$
$$x_{32} = -5.94036999057271$$
$$x_{33} = -15.5792364103872$$
$$x_{34} = 100.511065295271$$
$$x_{35} = 65.9431119046552$$
$$x_{36} = 5.94036999057271$$
$$x_{37} = 78.5143405319308$$
$$x_{38} = -97.368830362901$$
$$x_{39} = 37.6459603230864$$
$$x_{40} = -50.2256516491831$$
$$x_{41} = -69.0860849466452$$
$$x_{42} = -87.9418500396598$$
$$x_{43} = 21.8996964794928$$
$$x_{44} = -78.5143405319308$$
$$x_{45} = 131.931731514843$$
$$x_{46} = 62.8000005565198$$
$$x_{47} = 75.3716854092873$$
$$x_{48} = 91.0842274914688$$
$$x_{49} = -91.0842274914688$$
$$x_{50} = -59.6567290035279$$
$$x_{51} = 81.6569138240367$$
$$x_{52} = 31.3520917265645$$
$$x_{53} = 56.5132704621986$$
$$x_{54} = 40.7916552312719$$
$$x_{55} = -1288.05143523817$$
$$x_{56} = -34.499514921367$$
$$x_{57} = -47.0813974121542$$
$$x_{58} = -9.20584014293667$$
$$x_{59} = 84.7994143922025$$
$$x_{60} = -6000.4416350477$$
$$x_{61} = -56.5132704621986$$
$$x_{62} = 59.6567290035279$$
$$x_{63} = -12.404445021902$$
$$x_{64} = 69.0860849466452$$
$$x_{65} = 97.368830362901$$
$$x_{66} = -53.3695918204908$$
$$x_{67} = -84.7994143922025$$
$$x_{68} = -28.2033610039524$$
The values of the extrema at the points:
(9.205840142936665, -0.108596459650656)
(-25.052825280992952, -0.0399154551181168)
(-62.80000055651978, -0.0159235646903331)
(87.94185003965976, 0.0113711499827495)
(-100.51106529527117, -0.00994915313518948)
(2.0815759778181007, -0.436181817271459)
(-18.742645584774756, -0.0533533960683124)
(28.203361003952356, -0.0354566549305966)
(-2.0815759778181007, 0.436181817271459)
(18.742645584774756, 0.0533533960683124)
(43.93676147141978, 0.0227599720559271)
(72.22893776201543, -0.0138448654722319)
(-72.22893776201543, 0.0138448654722319)
(34.49951492136695, -0.028985873872906)
(-40.79165523127188, 0.0245148001959268)
(25.052825280992952, 0.0399154551181168)
(-342.4277585600899, 0.00292032399493412)
(-31.352091726564478, -0.0318957324684592)
(15.579236410387185, -0.0641858191861418)
(94.22655257456837, 0.0106127195286878)
(-65.94311190465524, 0.0151645845236782)
(-21.89969647949278, 0.045662336274346)
(47.08139741215418, -0.0212398027231513)
(-81.65691382403672, -0.0122463599000435)
(-75.37168540928732, -0.0132675809569274)
(50.22565164918307, 0.0199101386020246)
(12.404445021901974, 0.080609453740734)
(-37.64596032308639, -0.0265632486369092)
(-43.93676147141978, -0.0227599720559271)
(53.36959182049082, -0.0187372569166781)
(-94.22655257456837, -0.0106127195286878)
(-5.940369990572712, -0.168069959945503)
(-15.579236410387185, 0.0641858191861418)
(100.51106529527117, 0.00994915313518948)
(65.94311190465524, -0.0151645845236782)
(5.940369990572712, 0.168069959945503)
(78.51434053193078, -0.0127365260994994)
(-97.36883036290097, 0.0102702268685152)
(37.64596032308639, 0.0265632486369092)
(-50.22565164918307, -0.0199101386020246)
(-69.08608494664519, -0.0144746936083834)
(-87.94185003965976, -0.0113711499827495)
(21.89969647949278, -0.045662336274346)
(-78.51434053193078, 0.0127365260994994)
(131.93173151484254, 0.0075796776250613)
(62.80000055651978, 0.0159235646903331)
(75.37168540928732, 0.0132675809569274)
(91.08422749146878, -0.0109788489015426)
(-91.08422749146878, 0.0109788489015426)
(-59.656729003527936, 0.016762565745722)
(81.65691382403672, 0.0122463599000435)
(31.352091726564478, 0.0318957324684592)
(56.513270462198584, 0.0176949554634471)
(40.79165523127188, -0.0245148001959268)
(-1288.0514352381674, -0.000776366511958716)
(-34.49951492136695, 0.028985873872906)
(-47.08139741215418, 0.0212398027231513)
(-9.205840142936665, 0.108596459650656)
(84.79941439220251, -0.0117925338104037)
(-6000.4416350476995, -0.000166654399929356)
(-56.513270462198584, -0.0176949554634471)
(59.656729003527936, -0.016762565745722)
(-12.404445021901974, -0.080609453740734)
(69.08608494664519, 0.0144746936083834)
(97.36883036290097, -0.0102702268685152)
(-53.36959182049082, 0.0187372569166781)
(-84.79941439220251, 0.0117925338104037)
(-28.203361003952356, 0.0354566549305966)
Intervals of increase and decrease of the function:Let's find intervals where the function increases and decreases, as well as minima and maxima of the function, for this let's look how the function behaves itself in the extremas and at the slightest deviation from:
Minima of the function at points:
$$x_{1} = 9.20584014293667$$
$$x_{2} = -25.052825280993$$
$$x_{3} = -62.8000005565198$$
$$x_{4} = -100.511065295271$$
$$x_{5} = 2.0815759778181$$
$$x_{6} = -18.7426455847748$$
$$x_{7} = 28.2033610039524$$
$$x_{8} = 72.2289377620154$$
$$x_{9} = 34.499514921367$$
$$x_{10} = -31.3520917265645$$
$$x_{11} = 15.5792364103872$$
$$x_{12} = 47.0813974121542$$
$$x_{13} = -81.6569138240367$$
$$x_{14} = -75.3716854092873$$
$$x_{15} = -37.6459603230864$$
$$x_{16} = -43.9367614714198$$
$$x_{17} = 53.3695918204908$$
$$x_{18} = -94.2265525745684$$
$$x_{19} = -5.94036999057271$$
$$x_{20} = 65.9431119046552$$
$$x_{21} = 78.5143405319308$$
$$x_{22} = -50.2256516491831$$
$$x_{23} = -69.0860849466452$$
$$x_{24} = -87.9418500396598$$
$$x_{25} = 21.8996964794928$$
$$x_{26} = 91.0842274914688$$
$$x_{27} = 40.7916552312719$$
$$x_{28} = -1288.05143523817$$
$$x_{29} = 84.7994143922025$$
$$x_{30} = -6000.4416350477$$
$$x_{31} = -56.5132704621986$$
$$x_{32} = 59.6567290035279$$
$$x_{33} = -12.404445021902$$
$$x_{34} = 97.368830362901$$
Maxima of the function at points:
$$x_{34} = 87.9418500396598$$
$$x_{34} = -2.0815759778181$$
$$x_{34} = 18.7426455847748$$
$$x_{34} = 43.9367614714198$$
$$x_{34} = -72.2289377620154$$
$$x_{34} = -40.7916552312719$$
$$x_{34} = 25.052825280993$$
$$x_{34} = -342.42775856009$$
$$x_{34} = 94.2265525745684$$
$$x_{34} = -65.9431119046552$$
$$x_{34} = -21.8996964794928$$
$$x_{34} = 50.2256516491831$$
$$x_{34} = 12.404445021902$$
$$x_{34} = -15.5792364103872$$
$$x_{34} = 100.511065295271$$
$$x_{34} = 5.94036999057271$$
$$x_{34} = -97.368830362901$$
$$x_{34} = 37.6459603230864$$
$$x_{34} = -78.5143405319308$$
$$x_{34} = 131.931731514843$$
$$x_{34} = 62.8000005565198$$
$$x_{34} = 75.3716854092873$$
$$x_{34} = -91.0842274914688$$
$$x_{34} = -59.6567290035279$$
$$x_{34} = 81.6569138240367$$
$$x_{34} = 31.3520917265645$$
$$x_{34} = 56.5132704621986$$
$$x_{34} = -34.499514921367$$
$$x_{34} = -47.0813974121542$$
$$x_{34} = -9.20584014293667$$
$$x_{34} = 69.0860849466452$$
$$x_{34} = -53.3695918204908$$
$$x_{34} = -84.7994143922025$$
$$x_{34} = -28.2033610039524$$
Decreasing at intervals
$$\left[97.368830362901, \infty\right)$$
Increasing at intervals
$$\left(-\infty, -6000.4416350477\right]$$