Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative$$- \frac{\left(1 - \frac{x + 1}{x}\right) \left(\frac{\left(1 - \frac{x + 1}{x}\right) \cos^{2}{\left(\frac{x + 1}{x} \right)}}{\sin^{2}{\left(\frac{x + 1}{x} \right)}} + 1 + \frac{2 \cos{\left(\frac{x + 1}{x} \right)}}{\sin{\left(\frac{x + 1}{x} \right)}} - \frac{x + 1}{x}\right)}{x^{2}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = -37619.3545686907$$
$$x_{2} = -17285.2004868838$$
$$x_{3} = -29145.4491164473$$
$$x_{4} = 25124.0798150973$$
$$x_{5} = -24909.0083682467$$
$$x_{6} = 28512.8612251605$$
$$x_{7} = -40161.6952408713$$
$$x_{8} = -41009.1546436674$$
$$x_{9} = 2.65015178909654$$
$$x_{10} = -10513.3712666392$$
$$x_{11} = -38466.7948066258$$
$$x_{12} = 33596.6839801017$$
$$x_{13} = -32534.8840468669$$
$$x_{14} = -19826.1038624244$$
$$x_{15} = -29992.78810533$$
$$x_{16} = -20673.1684215191$$
$$x_{17} = -41856.619692791$$
$$x_{18} = -26603.5277227986$$
$$x_{19} = 36986.187305809$$
$$x_{20} = -25756.257379686$$
$$x_{21} = -33382.2724990834$$
$$x_{22} = -31687.5065751571$$
$$x_{23} = 29360.1190865123$$
$$x_{24} = -13051.8321522232$$
$$x_{25} = 34444.0421082968$$
$$x_{26} = -30840.1409439218$$
$$x_{27} = 12425.3206190295$$
$$x_{28} = -24061.7827999438$$
$$x_{29} = 17501.8790274786$$
$$x_{30} = -12205.5007320442$$
$$x_{31} = 24276.9610148229$$
$$x_{32} = 36138.7946409554$$
$$x_{33} = 23429.8799824117$$
$$x_{34} = -34229.6711531442$$
$$x_{35} = -35924.49630363$$
$$x_{36} = 27665.6259245305$$
$$x_{37} = 31054.6946908808$$
$$x_{38} = 19195.2328512772$$
$$x_{39} = 40375.850545569$$
$$x_{40} = -23214.5830743721$$
$$x_{41} = 35291.4126331202$$
$$x_{42} = 10735.3929268084$$
$$x_{43} = 42918.1792180365$$
$$x_{44} = 25971.2324363076$$
$$x_{45} = -22367.4119301332$$
$$x_{46} = 30207.3975006056$$
$$x_{47} = -14744.8903781776$$
$$x_{48} = -21520.2725068826$$
$$x_{49} = 20888.9133908379$$
$$x_{50} = 31902.0090797943$$
$$x_{51} = -28298.1251540893$$
$$x_{52} = -15591.5782730875$$
$$x_{53} = 37833.5898790521$$
$$x_{54} = 14962.7338995863$$
$$x_{55} = 26818.4154629745$$
$$x_{56} = 22582.8413037886$$
$$x_{57} = 39528.4220910983$$
$$x_{58} = -35077.0793023063$$
$$x_{59} = 18348.5088828194$$
$$x_{60} = 38681.0016805698$$
$$x_{61} = -18132.1136690833$$
$$x_{62} = -39314.2418350807$$
$$x_{63} = -36771.9215709389$$
$$x_{64} = 13270.8624176383$$
$$x_{65} = 16655.3592306802$$
$$x_{66} = 20042.0379258406$$
$$x_{67} = -13898.3025602372$$
$$x_{68} = 15808.9692557715$$
$$x_{69} = 42070.7295629554$$
$$x_{70} = -16438.3521624976$$
$$x_{71} = -27450.8175322709$$
$$x_{72} = -18979.0837069441$$
$$x_{73} = 11580.1312005378$$
$$x_{74} = 14116.6847040939$$
$$x_{75} = 21735.8503386482$$
$$x_{76} = 32749.3392617094$$
$$x_{77} = -11359.3355054836$$
$$x_{78} = 41223.2865273061$$
You also need to calculate the limits of y '' for arguments seeking to indeterminate points of a function:
Points where there is an indetermination:
$$x_{1} = 0$$
True
True
- the limits are not equal, so
$$x_{1} = 0$$
- is an inflection point
Сonvexity and concavity intervals:Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Concave at the intervals
$$\left[2.65015178909654, \infty\right)$$
Convex at the intervals
$$\left(-\infty, 2.65015178909654\right]$$