El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\tan^{2}{\left(4 x \right)} + \tan{\left(4 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
$$x_{2} = - \frac{\pi}{16}$$
Solución numérica$$x_{1} = -59.6902604182061$$
$$x_{2} = -55.7632696012188$$
$$x_{3} = 7.85398163397448$$
$$x_{4} = -45.7494430179014$$
$$x_{5} = 2.35619449019234$$
$$x_{6} = -21.9911485751286$$
$$x_{7} = -23.7582944427728$$
$$x_{8} = 50.2654824574367$$
$$x_{9} = 33.7721210260903$$
$$x_{10} = -54.1924732744239$$
$$x_{11} = -37.1100632205294$$
$$x_{12} = 38.484510006475$$
$$x_{13} = -32.2013246992954$$
$$x_{14} = -85.8047493511712$$
$$x_{15} = 95.8185759344887$$
$$x_{16} = -71.4712328691678$$
$$x_{17} = -67.7405915930299$$
$$x_{18} = -27.6852852597601$$
$$x_{19} = 86.1974484328699$$
$$x_{20} = 62.0464549083984$$
$$x_{21} = 91.8915851175014$$
$$x_{22} = 25.9181393921158$$
$$x_{23} = -1.76714586764426$$
$$x_{24} = 0$$
$$x_{25} = 43.9822971502571$$
$$x_{26} = -43.9822971502571$$
$$x_{27} = 24.3473430653209$$
$$x_{28} = 76.1836218495525$$
$$x_{29} = -58.1194640914112$$
$$x_{30} = -80.1106126665397$$
$$x_{31} = -65.9734457253857$$
$$x_{32} = -99.7455667514759$$
$$x_{33} = 64.2062998577414$$
$$x_{34} = 16.2970118904971$$
$$x_{35} = 38.2881604656256$$
$$x_{36} = -49.6764338348886$$
$$x_{37} = 51.8362787842316$$
$$x_{38} = -87.9645943005142$$
$$x_{39} = 46.3384916404494$$
$$x_{40} = -95.0331777710912$$
$$x_{41} = -14.1371669411541$$
$$x_{42} = -11.7809724509617$$
$$x_{43} = -3.92699081698724$$
$$x_{44} = 87.9645943005142$$
$$x_{45} = -73.8274273593601$$
$$x_{46} = -81.6814089933346$$
$$x_{47} = 72.2566310325652$$
$$x_{48} = -18.0641577581413$$
$$x_{49} = -98.174770424681$$
$$x_{50} = -29.845130209103$$
$$x_{51} = 9.42477796076938$$
$$x_{52} = -62.0464549083984$$
$$x_{53} = 60.2793090407542$$
$$x_{54} = 18.0641577581413$$
$$x_{55} = 29.845130209103$$
$$x_{56} = 11.7809724509617$$
$$x_{57} = 28.2743338823081$$
$$x_{58} = 69.9004365423729$$
$$x_{59} = -51.8362787842316$$
$$x_{60} = 20.2240027074843$$
$$x_{61} = 47.9092879672443$$
$$x_{62} = 54.1924732744239$$
$$x_{63} = 100.530964914873$$
$$x_{64} = -47.9092879672443$$
$$x_{65} = 94.2477796076938$$
$$x_{66} = 21.9911485751286$$
$$x_{67} = -36.1283155162826$$
$$x_{68} = -15.707963267949$$
$$x_{69} = -7.85398163397448$$
$$x_{70} = 65.9734457253857$$
$$x_{71} = 14.1371669411541$$
$$x_{72} = 40.0553063332699$$
$$x_{73} = 80.1106126665397$$
$$x_{74} = -84.037603483527$$
$$x_{75} = -25.9181393921158$$
$$x_{76} = -10.2101761241668$$
$$x_{77} = -91.8915851175014$$
$$x_{78} = -69.9004365423729$$
$$x_{79} = 36.1283155162826$$
$$x_{80} = 90.3207887907066$$
$$x_{81} = -5.6941366846315$$
$$x_{82} = -95.8185759344887$$
$$x_{83} = 6.28318530717959$$
$$x_{84} = 3.92699081698724$$
$$x_{85} = -77.7544181763474$$
$$x_{86} = -76.1836218495525$$
$$x_{87} = 57.1377163871644$$
$$x_{88} = 98.174770424681$$
$$x_{89} = -40.0553063332699$$
$$x_{90} = -37.6991118430775$$
$$x_{91} = 42.2151512826128$$
$$x_{92} = 73.8274273593601$$
$$x_{93} = -89.7317401681585$$
$$x_{94} = 58.1194640914112$$
$$x_{95} = 79.1288649622929$$
$$x_{96} = 68.329640215578$$
$$x_{97} = 82.2704576158827$$
$$x_{98} = -42.4115008234622$$
$$x_{99} = -33.7721210260903$$
$$x_{100} = 84.037603483527$$