El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\tan^{2}{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
Solución numérica$$x_{1} = 8.37758030791964$$
$$x_{2} = 4.18879026203989$$
$$x_{3} = -87.964594354958$$
$$x_{4} = -85.8701989969528$$
$$x_{5} = 96.3421746411896$$
$$x_{6} = 87.9645943393338$$
$$x_{7} = 50.2654824461567$$
$$x_{8} = -83.7758040753805$$
$$x_{9} = -99.4837677181245$$
$$x_{10} = 80.6342114335369$$
$$x_{11} = 94.2477796093492$$
$$x_{12} = -4.18878993041984$$
$$x_{13} = 6.28318528324973$$
$$x_{14} = 48.1710874415826$$
$$x_{15} = 74.3510260584389$$
$$x_{16} = -39.7935069087371$$
$$x_{17} = 65.9734457549079$$
$$x_{18} = -79.5870140333431$$
$$x_{19} = -17.8023583240562$$
$$x_{20} = -35.6047168614822$$
$$x_{21} = -57.595865447072$$
$$x_{22} = 85.8701993522284$$
$$x_{23} = 13.6135680608892$$
$$x_{24} = -13.6135682765058$$
$$x_{25} = 41.8879021757213$$
$$x_{26} = 26.1799388502105$$
$$x_{27} = -15.7079632982299$$
$$x_{28} = 28.2743338646959$$
$$x_{29} = 92.1533846449389$$
$$x_{30} = 30.3687288918511$$
$$x_{31} = -65.9734457628872$$
$$x_{32} = -24.0855435838322$$
$$x_{33} = 0$$
$$x_{34} = -46.0766921693115$$
$$x_{35} = -92.1533843102778$$
$$x_{36} = -55.5014705169195$$
$$x_{37} = -59.6902604614627$$
$$x_{38} = -48.1710871235236$$
$$x_{39} = -70.1622357176096$$
$$x_{40} = -81.6814090432967$$
$$x_{41} = 43.9822971703228$$
$$x_{42} = 36.651914438817$$
$$x_{43} = 32.4631238646887$$
$$x_{44} = -41.8879017335743$$
$$x_{45} = 59.6902604802496$$
$$x_{46} = 70.1622360382887$$
$$x_{47} = 19.8967535886007$$
$$x_{48} = 90.0589892683329$$
$$x_{49} = -33.510321919082$$
$$x_{50} = -2.09439499788865$$
$$x_{51} = 98.4365696364745$$
$$x_{52} = 17.8023586689732$$
$$x_{53} = 39.7935072705309$$
$$x_{54} = -37.699111879787$$
$$x_{55} = 63.8790507635645$$
$$x_{56} = 54.4542724564543$$
$$x_{57} = 72.2566310276868$$
$$x_{58} = -43.9822971736453$$
$$x_{59} = 68.067840619562$$
$$x_{60} = -77.4926191165746$$
$$x_{61} = 61.7846558744647$$
$$x_{62} = -26.1799385278539$$
$$x_{63} = 21.9911485854216$$
$$x_{64} = -11.519173322952$$
$$x_{65} = 76.4454210470121$$
$$x_{66} = 52.3598774753413$$
$$x_{67} = -8.37758020464329$$
$$x_{68} = -68.0678407544063$$
$$x_{69} = -61.7846554924188$$
$$x_{70} = -21.9911485862214$$
$$x_{71} = 10.4719752715954$$
$$x_{72} = -90.058989339196$$