El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left(\cos{\left(\frac{3 x}{2} \right)} - 4 \tan{\left(\frac{7 x}{5} \right)}\right) + 2 \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución numérica$$x_{1} = 84.9325944945931$$
$$x_{2} = 89.9028057895237$$
$$x_{3} = 58.7812088507375$$
$$x_{4} = 29.5625277672296$$
$$x_{5} = 17.6718641206128$$
$$x_{6} = -56.1320256604007$$
$$x_{7} = -4.05064422105831$$
$$x_{8} = -53.8417146510988$$
$$x_{9} = -78.7583450010068$$
$$x_{10} = 98.7710819165942$$
$$x_{11} = 51.2870620494496$$
$$x_{12} = 19.8584893050998$$
$$x_{13} = -51.7820359076097$$
$$x_{14} = 33.9171289775654$$
$$x_{15} = -87.4185211894687$$
$$x_{16} = -49.5143571619503$$
$$x_{17} = -45.1599889511831$$
$$x_{18} = -85.3735408270606$$
$$x_{19} = 71.8219914924929$$
$$x_{20} = 27.0709527177278$$
$$x_{21} = 11.0498171641862$$
$$x_{22} = -74.3766440941422$$
$$x_{23} = 101.077038025919$$
$$x_{24} = 38.245184954123$$
$$x_{25} = -89.7244772987934$$
$$x_{26} = 96.7489820493613$$
$$x_{27} = -96.1011783763622$$
$$x_{28} = 73.881670235982$$
$$x_{29} = 35.9392288447983$$
$$x_{30} = -37.6883999289649$$
$$x_{31} = 87.9753062146268$$
$$x_{32} = -13.7927760582612$$
$$x_{33} = 80.5037171924087$$
$$x_{34} = 6.69982741139512$$
$$x_{35} = -11.5447910223463$$
$$x_{36} = -6.99835242500681$$
$$x_{37} = -81.0178401493829$$
$$x_{38} = -71.3839784740616$$
$$x_{39} = -35.760900354068$$
$$x_{40} = -58.1647693699612$$
$$x_{41} = -26.8926242269975$$
$$x_{42} = 46.9053611425849$$
$$x_{43} = -24.5866681176728$$
$$x_{44} = 55.8335006467891$$
$$x_{45} = 49.0390770135346$$
$$x_{46} = 31.562659053951$$
$$x_{47} = -91.7465771660263$$
$$x_{48} = -47.4130298759535$$
$$x_{49} = -98.5927534258639$$
$$x_{50} = 369.992766005768$$
$$x_{51} = -20.2638729869544$$
$$x_{52} = 60.7620432666152$$
$$x_{53} = 22.1007414227972$$
$$x_{54} = -64.9016628769765$$
$$x_{55} = -62.5029880863205$$
$$x_{56} = -15.926491929211$$
$$x_{57} = 2.34080797399164$$
$$x_{58} = -60.4910450978042$$
$$x_{59} = 76.1493489816415$$
$$x_{60} = 4.66708370183464$$
$$x_{61} = 8.99013842069702$$
$$x_{62} = -22.5416877552647$$
$$x_{63} = 44.6458659942089$$
$$x_{64} = 13.3174959098456$$
$$x_{65} = 54.2797276695301$$
$$x_{66} = -94.1010470896408$$
$$x_{67} = 92.3943808390254$$
$$x_{68} = -69.8302054968027$$
$$x_{69} = 69.531680483191$$
$$x_{70} = 40.2901653165311$$
$$x_{71} = 42.5679800848415$$
$$x_{72} = -42.9733637666961$$
$$x_{73} = -2.06980980518066$$
$$x_{74} = 65.1726610457875$$
$$x_{75} = 0.328864985475325$$
$$x_{76} = -83.0957260587503$$
$$x_{77} = 82.6903423768957$$
$$x_{78} = 94.3945121257468$$
$$x_{79} = -18.185987077587$$
$$x_{80} = 78.2506762676382$$
$$x_{81} = 67.4989367736305$$
$$x_{82} = -31.2691940178449$$
$$x_{83} = -28.9147240942305$$