El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$e^{3 x} \cos{\left(2 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{3 \pi}{4}$$
$$x_{2} = - \frac{\pi}{4}$$
$$x_{3} = \frac{\pi}{4}$$
$$x_{4} = \frac{3 \pi}{4}$$
Solución numérica$$x_{1} = -74.6128255227576$$
$$x_{2} = -46.3384916404494$$
$$x_{3} = -63.6172512351933$$
$$x_{4} = -55.7632696012188$$
$$x_{5} = -73.0420291959627$$
$$x_{6} = -90.3207887907066$$
$$x_{7} = -98.174770424681$$
$$x_{8} = -38.484510006475$$
$$x_{9} = -91.8915851175014$$
$$x_{10} = -68.329640215578$$
$$x_{11} = -51.0508806208341$$
$$x_{12} = -10.2101761241668$$
$$x_{13} = -96.6039740978861$$
$$x_{14} = -18.0641577581413$$
$$x_{15} = 7.06858347057703$$
$$x_{16} = 5.49778714378214$$
$$x_{17} = -52.621676947629$$
$$x_{18} = -11.7809724509617$$
$$x_{19} = -0.785398163397448$$
$$x_{20} = -54.1924732744239$$
$$x_{21} = -85.6083998103219$$
$$x_{22} = -40.0553063332699$$
$$x_{23} = 3.92699081698724$$
$$x_{24} = -47.9092879672443$$
$$x_{25} = -2.35619449019234$$
$$x_{26} = -30.6305283725005$$
$$x_{27} = -99.7455667514759$$
$$x_{28} = -36.9137136796801$$
$$x_{29} = -16.4933614313464$$
$$x_{30} = -8.63937979737193$$
$$x_{31} = 10.2101761241668$$
$$x_{32} = -66.7588438887831$$
$$x_{33} = -41.6261026600648$$
$$x_{34} = -22.776546738526$$
$$x_{35} = -44.7676953136546$$
$$x_{36} = -77.7544181763474$$
$$x_{37} = -69.9004365423729$$
$$x_{38} = -58.9048622548086$$
$$x_{39} = -76.1836218495525$$
$$x_{40} = -25.9181393921158$$
$$x_{41} = -19.6349540849362$$
$$x_{42} = -14.9225651045515$$
$$x_{43} = 2.35619449019234$$
$$x_{44} = -62.0464549083984$$
$$x_{45} = -84.037603483527$$
$$x_{46} = -82.4668071567321$$
$$x_{47} = -24.3473430653209$$
$$x_{48} = -60.4756585816035$$
$$x_{49} = -3.92699081698724$$
$$x_{50} = -80.8960108299372$$
$$x_{51} = -88.7499924639117$$
$$x_{52} = -32.2013246992954$$
$$x_{53} = -95.0331777710912$$
$$x_{54} = -33.7721210260903$$
$$x_{55} = -29.0597320457056$$
$$x_{56} = -7.06858347057703$$