El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$- 2 \sin{\left(6 x \right)} + \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{5 \pi}{6}$$
$$x_{2} = - \frac{\pi}{2}$$
$$x_{3} = - \frac{\pi}{6}$$
$$x_{4} = \frac{\pi}{6}$$
$$x_{5} = \frac{\pi}{2}$$
$$x_{6} = \frac{5 \pi}{6}$$
Solución numérica$$x_{1} = -75.9218224617533$$
$$x_{2} = 40.317105721069$$
$$x_{3} = 78.0162175641465$$
$$x_{4} = 28.1901071305941$$
$$x_{5} = -34.0339204138894$$
$$x_{6} = -59.7744871699201$$
$$x_{7} = 46.1609190043643$$
$$x_{8} = 41.9721287995779$$
$$x_{9} = -5.75958653158129$$
$$x_{10} = -19.9809802244494$$
$$x_{11} = -97.9129710368819$$
$$x_{12} = -9.94837673636768$$
$$x_{13} = 37.1755130674792$$
$$x_{14} = 7.24615610666216$$
$$x_{15} = 12.0427718387609$$
$$x_{16} = 88.0488210522282$$
$$x_{17} = -95.8185759344887$$
$$x_{18} = 50.3497092091507$$
$$x_{19} = 100.007366139275$$
$$x_{20} = -49.7418836818384$$
$$x_{21} = -53.9306738866248$$
$$x_{22} = -92.6769832808989$$
$$x_{23} = -43.8980703985431$$
$$x_{24} = -45.9924655009363$$
$$x_{25} = 71.733032256967$$
$$x_{26} = -56.025068989018$$
$$x_{27} = 36.1283155162826$$
$$x_{28} = -24.1697704292358$$
$$x_{29} = -29.845130209103$$
$$x_{30} = 58.1194640914112$$
$$x_{31} = 72.1724042808512$$
$$x_{32} = -15.792190019663$$
$$x_{33} = -37.6148850913635$$
$$x_{34} = 31.9395253114962$$
$$x_{35} = 2.17862185410722$$
$$x_{36} = 30.2845022329873$$
$$x_{37} = 67.9836140760648$$
$$x_{38} = 16.2315620435473$$
$$x_{39} = -81.1578102177363$$
$$x_{40} = 60.2138591938044$$
$$x_{41} = 90.1432161546214$$
$$x_{42} = 80.1106126665397$$
$$x_{43} = -36.7361410435949$$
$$x_{44} = -68.5914396033772$$
$$x_{45} = -12.0427718387609$$
$$x_{46} = 82.2050077689329$$
$$x_{47} = -87.8803675488002$$
$$x_{48} = 56.025068989018$$
$$x_{49} = -57.0722665402146$$
$$x_{50} = -4.10456345307237$$
$$x_{51} = 26.0957120282009$$
$$x_{52} = 34.0339204138894$$
$$x_{53} = -61.8688822723133$$
$$x_{54} = 14.1371669411541$$
$$x_{55} = 84.2994028713261$$
$$x_{56} = -13.6977949172698$$
$$x_{57} = -17.8865851220562$$
$$x_{58} = 85.954425949835$$
$$x_{59} = -89.9747626511934$$
$$x_{60} = 53.9306738866248$$
$$x_{61} = -25.6563400043166$$
$$x_{62} = 65.8892189736716$$
$$x_{63} = 75.4824504378691$$
$$x_{64} = -78.0162175641465$$
$$x_{65} = 44.0665239019711$$
$$x_{66} = 6.36741205889361$$
$$x_{67} = 0.0842267517140262$$
$$x_{68} = 94.3320063594078$$
$$x_{69} = 4.27301695650042$$
$$x_{70} = -83.6915773440138$$
$$x_{71} = 38.2227106186758$$
$$x_{72} = -22.0753753268426$$
$$x_{73} = 9.94837673636768$$
$$x_{74} = -51.8362787842316$$
$$x_{75} = -63.9632773747065$$
$$x_{76} = 21.9069218234145$$
$$x_{77} = 18.3259571459405$$
$$x_{78} = 48.2553141067575$$
$$x_{79} = -100.007366139275$$
$$x_{80} = -41.8036752961499$$
$$x_{81} = -73.8274273593601$$
$$x_{82} = -93.7241808320955$$
$$x_{83} = -85.785972446407$$
$$x_{84} = 74.2667993832444$$
$$x_{85} = 62.3082542961976$$
$$x_{86} = -66.0576724770997$$
$$x_{87} = 70.078009178458$$
$$x_{88} = -71.733032256967$$
$$x_{89} = 24.0013169258077$$
$$x_{90} = 92.2376112570146$$
$$x_{91} = -27.7507351067098$$
$$x_{92} = -69.6386371545737$$
$$x_{93} = 97.9129710368819$$
$$x_{94} = 69.1992651306895$$
$$x_{95} = -39.7092801937567$$
$$x_{96} = -2.01016835067917$$
$$x_{97} = -31.9395253114962$$
$$x_{98} = -80.1106126665397$$
$$x_{99} = -7.85398163397448$$