El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\sin{\left(3^{x} \right)} \cos^{2}{\left(3^{x} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{- \log{\left(2 \right)} + \log{\left(\pi \right)}}{\log{\left(3 \right)}}$$
Solución numérica$$x_{1} = -62.9855570613729$$
$$x_{2} = 1.04197804599219$$
$$x_{3} = -88.9855570613729$$
$$x_{4} = -442.08560371662$$
$$x_{5} = -32.985557061373$$
$$x_{6} = 6.14627068185093$$
$$x_{7} = -76.9855570613729$$
$$x_{8} = -50.9855570613729$$
$$x_{9} = -26.9855571384779$$
$$x_{10} = -74.9855570613729$$
$$x_{11} = -78.9855570613729$$
$$x_{12} = -34.9855570613729$$
$$x_{13} = -118.985557061373$$
$$x_{14} = -80.9855570613729$$
$$x_{15} = -60.9855570613729$$
$$x_{16} = -52.9855570613729$$
$$x_{17} = -108.985557061373$$
$$x_{18} = -64.9855570613729$$
$$x_{19} = -98.9855570613729$$
$$x_{20} = -86.9855570613729$$
$$x_{21} = -90.9855570613729$$
$$x_{22} = -46.9855570613729$$
$$x_{23} = -92.9855570613729$$
$$x_{24} = -82.9855570613729$$
$$x_{25} = -116.985557061373$$
$$x_{26} = -56.9855570613729$$
$$x_{27} = -112.985557061373$$
$$x_{28} = -30.9855570613846$$
$$x_{29} = -96.9855570613729$$
$$x_{30} = -65.8722042583592$$
$$x_{31} = -104.985557061373$$
$$x_{32} = -46.5142198696919$$
$$x_{33} = -94.9855570613729$$
$$x_{34} = -114.985557061373$$
$$x_{35} = -100.985557061373$$
$$x_{36} = -36.9855570613729$$
$$x_{37} = -106.985557061373$$
$$x_{38} = -44.9855570613729$$
$$x_{39} = -44.5681082097861$$
$$x_{40} = -68.9855570613729$$
$$x_{41} = -38.9855570613729$$
$$x_{42} = -72.9855570613729$$
$$x_{43} = -24.9855633069$$
$$x_{44} = -48.9855570613729$$
$$x_{45} = -478.847008394751$$
$$x_{46} = 27.2572019705977$$
$$x_{47} = -102.985557061373$$
$$x_{48} = 10.1445163508567$$
$$x_{49} = -58.9855570613729$$
$$x_{50} = -84.9855570613729$$
$$x_{51} = -42.9855570613729$$
$$x_{52} = -70.9855570613729$$
$$x_{53} = -54.9855570613729$$
$$x_{54} = -40.9855570613729$$
$$x_{55} = 0.411048229943712$$
$$x_{56} = -110.985557061373$$
$$x_{57} = -14527.0525026075$$
$$x_{58} = -66.9855570613729$$
$$x_{59} = -28.9855570623248$$