El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\cos{\left(3 - 4 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{3}{4} + \frac{3 \pi}{8}$$
$$x_{2} = \frac{\pi}{8} + \frac{3}{4}$$
Solución numérica$$x_{1} = 8.99668071567321$$
$$x_{2} = 100.102867669777$$
$$x_{3} = 49.8373852123405$$
$$x_{4} = -45.9811907221482$$
$$x_{5} = -53.8351723561227$$
$$x_{6} = -56.191366846315$$
$$x_{7} = 56.1205705195201$$
$$x_{8} = -60.1183576633022$$
$$x_{9} = 45.9103943953533$$
$$x_{10} = 63.9745521534946$$
$$x_{11} = 15.2798660228528$$
$$x_{12} = 81.2533117482384$$
$$x_{13} = -65.6161448070844$$
$$x_{14} = 85.9657007286231$$
$$x_{15} = 18.4214586764426$$
$$x_{16} = 430.755494460103$$
$$x_{17} = -83.6803025652257$$
$$x_{18} = 96.17587685279$$
$$x_{19} = 40.4126072515711$$
$$x_{20} = 62.4037558266997$$
$$x_{21} = -47.5519870489431$$
$$x_{22} = 4.28429173528852$$
$$x_{23} = 66.3307466436869$$
$$x_{24} = 67.9015429704818$$
$$x_{25} = 84.3949044018282$$
$$x_{26} = 23.9192458202247$$
$$x_{27} = -82.1095062384308$$
$$x_{28} = 16.0652641862502$$
$$x_{29} = 26.2754403104171$$
$$x_{30} = -13.7798660228528$$
$$x_{31} = 41.983403578366$$
$$x_{32} = -52.2643760293278$$
$$x_{33} = 34.1294219443916$$
$$x_{34} = 70.2577374606742$$
$$x_{35} = 44.3395980685584$$
$$x_{36} = 78.1117190946487$$
$$x_{37} = 49.0519870489431$$
$$x_{38} = 89.8926915456104$$
$$x_{39} = -25.5608384738145$$
$$x_{40} = 38.0564127613788$$
$$x_{41} = -49.9081815391354$$
$$x_{42} = -78.1825154214436$$
$$x_{43} = -67.9723392972767$$
$$x_{44} = 5.85508806208341$$
$$x_{45} = -71.899330114264$$
$$x_{46} = -34.2002182711865$$
$$x_{47} = -20.0630513300324$$
$$x_{48} = -35.7710145979813$$
$$x_{49} = -100.173663996572$$
$$x_{50} = -64.0453484802895$$
$$x_{51} = -202.27542523824$$
$$x_{52} = -23.9900421470196$$
$$x_{53} = -39.6980054149686$$
$$x_{54} = -90.7488860358027$$
$$x_{55} = 52.1935797025329$$
$$x_{56} = -86.036497055418$$
$$x_{57} = -1.99889357189107$$
$$x_{58} = 71.8285337874691$$
$$x_{59} = -17.70685683984$$
$$x_{60} = -3.56968989868597$$
$$x_{61} = 60.0475613365073$$
$$x_{62} = -93.8904786893925$$
$$x_{63} = -79.7533117482384$$
$$x_{64} = -38.1272090881737$$
$$x_{65} = -98.6028676697772$$
$$x_{66} = 30.2024311274043$$
$$x_{67} = -42.0541999051609$$
$$x_{68} = -87.6072933822129$$
$$x_{69} = -97.8174695063798$$
$$x_{70} = 82.0387099116359$$
$$x_{71} = -5.92588438887831$$
$$x_{72} = -27.9170329640069$$
$$x_{73} = -9.85287520586555$$
$$x_{74} = -57.7621631731099$$
$$x_{75} = -16.1360605130451$$
$$x_{76} = 22.3484494934298$$
$$x_{77} = -89.9634878724053$$
$$x_{78} = -31.8440237809941$$
$$x_{79} = 93.8196823625976$$
$$x_{80} = 19.9922550032375$$
$$x_{81} = 74.1847282776614$$
$$x_{82} = 8.21128255227576$$
$$x_{83} = 0.357300918301276$$
$$x_{84} = 48.2665888855456$$
$$x_{85} = 1.92809724509617$$
$$x_{86} = -61.6891539900971$$
$$x_{87} = 12.138273369263$$
$$x_{88} = -43.6249962319558$$
$$x_{89} = 27.846236637212$$
$$x_{90} = 88.3218952188155$$
$$x_{91} = 92.2488860358027$$
$$x_{92} = -21.6338476568273$$
$$x_{93} = 74.9701264410589$$
$$x_{94} = -75.8263209312512$$