El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\tan^{4}{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
Solución numérica$$x_{1} = 94.2477860035851$$
$$x_{2} = -59.69043517874$$
$$x_{3} = 92.1537359418608$$
$$x_{4} = 43.9823594780185$$
$$x_{5} = -65.973539547391$$
$$x_{6} = 21.9911797097763$$
$$x_{7} = 90.0587694397639$$
$$x_{8} = -2.09405066421591$$
$$x_{9} = -68.0675978772886$$
$$x_{10} = -90.0587791248655$$
$$x_{11} = -21.9911797117032$$
$$x_{12} = 70.1625295688477$$
$$x_{13} = -87.9647201056628$$
$$x_{14} = 6.28308926296591$$
$$x_{15} = 28.2742636093252$$
$$x_{16} = -37.6992600727679$$
$$x_{17} = 46.0763632582965$$
$$x_{18} = 0$$
$$x_{19} = -83.7757295012906$$
$$x_{20} = 74.3507215495199$$
$$x_{21} = -15.7080852788385$$
$$x_{22} = -81.6816106600328$$
$$x_{23} = 50.2654378139692$$
$$x_{24} = 26.180152714109$$
$$x_{25} = -43.9823595111936$$
$$x_{26} = 68.0675751868478$$
$$x_{27} = 4.18897295339476$$
$$x_{28} = -46.0764161137832$$
$$x_{29} = -39.7933800116005$$
$$x_{30} = -24.0852337420097$$
$$x_{31} = 65.9735393584754$$
$$x_{32} = -61.7845549812787$$
$$x_{33} = 48.1713370707213$$
$$x_{34} = 87.9647194071339$$
$$x_{35} = -17.8022042431407$$
$$x_{36} = 96.3418990045115$$
$$x_{37} = 52.3595433752384$$
$$x_{38} = 72.2566119284032$$