Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$\tan^{2}{\left(4 x \right)} = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = 0$$
Numerical solution$$x_{1} = -62.0464548538807$$
$$x_{2} = -36.1283153226971$$
$$x_{3} = 90.320788735349$$
$$x_{4} = 6.28318528262228$$
$$x_{5} = -23.5619451232182$$
$$x_{6} = 87.9645943416767$$
$$x_{7} = -43.9822971730515$$
$$x_{8} = 82.4668069120011$$
$$x_{9} = -65.9734457615098$$
$$x_{10} = 50.2654824460375$$
$$x_{11} = -14.1371667262421$$
$$x_{12} = -3.92699109852159$$
$$x_{13} = 29.845130469522$$
$$x_{14} = 24.347342983671$$
$$x_{15} = -63.6172513615354$$
$$x_{16} = -29.845130062694$$
$$x_{17} = 28.2743338643801$$
$$x_{18} = -7.85398142254902$$
$$x_{19} = 20.4203520591665$$
$$x_{20} = 94.2477796093471$$
$$x_{21} = 60.4756583546577$$
$$x_{22} = 33.7721212629029$$
$$x_{23} = 72.2566310276665$$
$$x_{24} = -84.037603439755$$
$$x_{25} = 54.1924733267508$$
$$x_{26} = -33.7721210090001$$
$$x_{27} = 36.128315793064$$
$$x_{28} = -94.2477795727592$$
$$x_{29} = 65.9734457562088$$
$$x_{30} = -40.0553062675254$$
$$x_{31} = -5.49778706564407$$
$$x_{32} = 47.9092880853601$$
$$x_{33} = -45.5530937122474$$
$$x_{34} = -67.5442422970135$$
$$x_{35} = 21.9911485855647$$
$$x_{36} = 0$$
$$x_{37} = -81.6814090467211$$
$$x_{38} = -19.6349541873064$$
$$x_{39} = -87.9645943524031$$
$$x_{40} = -77.7544181730488$$
$$x_{41} = 69.900436676108$$
$$x_{42} = 18.0641575980835$$
$$x_{43} = -11.7809724263829$$
$$x_{44} = 38.4845098235765$$
$$x_{45} = -41.62610277398$$
$$x_{46} = -21.991148586076$$
$$x_{47} = 14.1371670560163$$
$$x_{48} = -59.69026046391$$
$$x_{49} = -58.1194639178135$$
$$x_{50} = 77.7544182462014$$
$$x_{51} = -55.7632695911703$$
$$x_{52} = 99.7455665024765$$
$$x_{53} = 16.4933613318976$$
$$x_{54} = 91.891585268117$$
$$x_{55} = -37.6991118814587$$
$$x_{56} = 64.4026492408947$$
$$x_{57} = 43.9822971708964$$
$$x_{58} = 7.85398187132473$$
$$x_{59} = 10.2101761568911$$
$$x_{60} = 84.0376034271735$$
$$x_{61} = 98.1747705056141$$
$$x_{62} = -99.745566754756$$
$$x_{63} = -80.1106125115255$$
$$x_{64} = 62.0464548306542$$
$$x_{65} = 46.3384915681264$$
$$x_{66} = 42.4115006503654$$
$$x_{67} = 51.8362790674845$$
$$x_{68} = -51.8362786747725$$
$$x_{69} = -73.8274272737004$$
$$x_{70} = -1.57079653228711$$
$$x_{71} = -15.7079632993025$$
$$x_{72} = -95.8185758659514$$
$$x_{73} = 76.1836219145007$$
$$x_{74} = 32.2013247411198$$
$$x_{75} = -89.5353908736038$$
$$x_{76} = -18.0641576805559$$
$$x_{77} = 68.3296401519947$$
$$x_{78} = 55.7632697711785$$
$$x_{79} = 40.0553062249401$$
$$x_{80} = 86.3937978305559$$
$$x_{81} = 2.35619439855232$$
$$x_{82} = 3.92699090715964$$
$$x_{83} = -85.6083999500216$$
$$x_{84} = 25.918139495754$$