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1-2*cos(3x)+5*cos(3x)+1=0 la ecuación

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Solución numérica:

Buscar la solución numérica en el intervalo [, ]

Solución

Ha introducido [src]
1 - 2*cos(3*x) + 5*cos(3*x) + 1 = 0
$$\left(\left(1 - 2 \cos{\left(3 x \right)}\right) + 5 \cos{\left(3 x \right)}\right) + 1 = 0$$
Solución detallada
Tenemos la ecuación
$$\left(\left(1 - 2 \cos{\left(3 x \right)}\right) + 5 \cos{\left(3 x \right)}\right) + 1 = 0$$
es la ecuación trigonométrica más simple
Transportemos 2 al miembro derecho de la ecuación

cambiando el signo de 2

Obtenemos:
$$3 \cos{\left(3 x \right)} = -2$$
Dividamos ambos miembros de la ecuación en 3

La ecuación se convierte en
$$\cos{\left(3 x \right)} = - \frac{2}{3}$$
Esta ecuación se reorganiza en
$$3 x = \pi n + \operatorname{acos}{\left(- \frac{2}{3} \right)}$$
$$3 x = \pi n - \pi + \operatorname{acos}{\left(- \frac{2}{3} \right)}$$
O
$$3 x = \pi n + \operatorname{acos}{\left(- \frac{2}{3} \right)}$$
$$3 x = \pi n - \pi + \operatorname{acos}{\left(- \frac{2}{3} \right)}$$
, donde n es cualquier número entero
Dividamos ambos miembros de la ecuación obtenida en
$$3$$
obtenemos la respuesta:
$$x_{1} = \frac{\pi n}{3} + \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3}$$
$$x_{2} = \frac{\pi n}{3} - \frac{\pi}{3} + \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3}$$
Gráfica
Suma y producto de raíces [src]
suma
  acos(-2/3)   2*pi   acos(-2/3)
- ---------- + ---- + ----------
      3         3         3     
$$\frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3} + \left(- \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3} + \frac{2 \pi}{3}\right)$$
=
2*pi
----
 3  
$$\frac{2 \pi}{3}$$
producto
/  acos(-2/3)   2*pi\ acos(-2/3)
|- ---------- + ----|*----------
\      3         3  /     3     
$$\left(- \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3} + \frac{2 \pi}{3}\right) \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3}$$
=
(-acos(-2/3) + 2*pi)*acos(-2/3)
-------------------------------
               9               
$$\frac{\left(- \operatorname{acos}{\left(- \frac{2}{3} \right)} + 2 \pi\right) \operatorname{acos}{\left(- \frac{2}{3} \right)}}{9}$$
(-acos(-2/3) + 2*pi)*acos(-2/3)/9
Respuesta rápida [src]
       acos(-2/3)   2*pi
x1 = - ---------- + ----
           3         3  
$$x_{1} = - \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3} + \frac{2 \pi}{3}$$
     acos(-2/3)
x2 = ----------
         3     
$$x_{2} = \frac{\operatorname{acos}{\left(- \frac{2}{3} \right)}}{3}$$
x2 = acos(-2/3)/3
Respuesta numérica [src]
x1 = -27.9939776587855
x2 = -13.8939243890784
x3 = -23.8051874539991
x4 = 76.165065013829
x5 = -76.165065013829
x6 = -49.4986411297627
x7 = 7.61073908189883
x8 = -62.0650117441219
x9 = 89.2921480752335
x10 = 48.9379286827174
x11 = -5.51634397950563
x12 = -65.693089501863
x13 = -11.7995292866852
x14 = 57.8762215393355
x15 = -30.0883727611787
x16 = 34.2771629659651
x17 = 32.1827678635719
x18 = 82.4482503210086
x19 = -55.7818264369423
x20 = -91.3865431776266
x21 = 53.6874313345491
x22 = 80.3538552186154
x23 = 30.0883727611787
x24 = -69.8818797066494
x25 = -47.4042460273695
x26 = -377.757959758449
x27 = -82.4482503210086
x28 = -99.7641235871994
x29 = 68.3481970513015
x30 = 22.2715047986512
x31 = -21.7107923516059
x32 = 18.0827145938648
x33 = 1.32755377471924
x34 = -67.7874846042562
x35 = -86.637040525795
x36 = 40.5603482731447
x37 = 95.575333382413
x38 = -34.2771629659651
x39 = 51.5930362321559
x40 = -45.3098509249763
x41 = 62.0650117441219
x42 = -95.575333382413
x43 = 74.0706699114358
x44 = -71.9762748090426
x45 = 92.9202258329746
x46 = -3.42194887711244
x47 = 15.9883194914716
x48 = 71.9762748090426
x49 = 38.4659531707515
x50 = 36.3715580683583
x51 = 69.8818797066494
x52 = -101.858518689593
x53 = -57.8762215393355
x54 = -59.9706166417287
x55 = -25.8995825563923
x56 = 59.9706166417287
x57 = 42.6547433755379
x58 = 13.8939243890784
x59 = 66.2538019489083
x60 = 97.6697284848062
x61 = 99.7641235871994
x62 = -39.0266656177968
x63 = 25.8995825563923
x64 = 59.4099041946834
x65 = -19.6163972492127
x66 = -18.0827145938648
x67 = -93.4809382800198
x68 = -9.70513418429202
x69 = -53.6874313345491
x70 = -36.3715580683583
x71 = 64.1594068465151
x72 = 4.95563153246035
x73 = -80.3538552186154
x74 = -51.5930362321559
x75 = -32.1827678635719
x76 = 11.7995292866852
x77 = 45.3098509249763
x78 = 86.637040525795
x79 = 78.2594601162222
x80 = -97.6697284848062
x81 = -15.9883194914716
x82 = 9.70513418429202
x83 = 24.3658999010444
x84 = 84.5426454234018
x85 = 55.7818264369423
x86 = 20.177109696258
x87 = -111.769781754513
x88 = -74.0706699114358
x89 = -1.32755377471924
x90 = -78.2594601162222
x91 = 27.9939776587855
x92 = -7.61073908189883
x92 = -7.61073908189883