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cos(2*x)-5*sin(x)-3=0

cos(2*x)-5*sin(x)-3=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
cos(2*x) - 5*sin(x) - 3 = 0
$$\left(- 5 \sin{\left(x \right)} + \cos{\left(2 x \right)}\right) - 3 = 0$$
Solución detallada
Tenemos la ecuación
$$\left(- 5 \sin{\left(x \right)} + \cos{\left(2 x \right)}\right) - 3 = 0$$
cambiamos
$$- 5 \sin{\left(x \right)} + \cos{\left(2 x \right)} - 3 = 0$$
$$- 2 \sin^{2}{\left(x \right)} - 5 \sin{\left(x \right)} - 2 = 0$$
Sustituimos
$$w = \sin{\left(x \right)}$$
Es la ecuación de la forma
a*w^2 + b*w + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = -2$$
$$b = -5$$
$$c = -2$$
, entonces
D = b^2 - 4 * a * c = 

(-5)^2 - 4 * (-2) * (-2) = 9

Como D > 0 la ecuación tiene dos raíces.
w1 = (-b + sqrt(D)) / (2*a)

w2 = (-b - sqrt(D)) / (2*a)

o
$$w_{1} = -2$$
$$w_{2} = - \frac{1}{2}$$
hacemos cambio inverso
$$\sin{\left(x \right)} = w$$
Tenemos la ecuación
$$\sin{\left(x \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
O
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, donde n es cualquier número entero
sustituimos w:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(-2 \right)}$$
$$x_{1} = 2 \pi n - \operatorname{asin}{\left(2 \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(- \frac{1}{2} \right)}$$
$$x_{2} = 2 \pi n - \frac{\pi}{6}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n + \pi - \operatorname{asin}{\left(-2 \right)}$$
$$x_{3} = 2 \pi n + \pi + \operatorname{asin}{\left(2 \right)}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(- \frac{1}{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \frac{7 \pi}{6}$$
Gráfica
Suma y producto de raíces [src]
suma
  5*pi   pi     pi        /      ___\     pi        /      ___\
- ---- - -- + - -- - I*log\2 - \/ 3 / + - -- - I*log\2 + \/ 3 /
   6     6      2                         2                    
$$\left(- \frac{\pi}{2} - i \log{\left(\sqrt{3} + 2 \right)}\right) + \left(\left(- \frac{5 \pi}{6} - \frac{\pi}{6}\right) + \left(- \frac{\pi}{2} - i \log{\left(2 - \sqrt{3} \right)}\right)\right)$$
=
             /      ___\        /      ___\
-2*pi - I*log\2 + \/ 3 / - I*log\2 - \/ 3 /
$$- 2 \pi - i \log{\left(\sqrt{3} + 2 \right)} - i \log{\left(2 - \sqrt{3} \right)}$$
producto
-5*pi -pi  /  pi        /      ___\\ /  pi        /      ___\\
-----*----*|- -- - I*log\2 - \/ 3 /|*|- -- - I*log\2 + \/ 3 /|
  6    6   \  2                    / \  2                    /
$$- \frac{5 \pi}{6} \left(- \frac{\pi}{6}\right) \left(- \frac{\pi}{2} - i \log{\left(2 - \sqrt{3} \right)}\right) \left(- \frac{\pi}{2} - i \log{\left(\sqrt{3} + 2 \right)}\right)$$
=
    2 /            /      ___\\ /            /      ___\\
5*pi *\pi + 2*I*log\2 + \/ 3 //*\pi + 2*I*log\2 - \/ 3 //
---------------------------------------------------------
                           144                           
$$\frac{5 \pi^{2} \left(\pi + 2 i \log{\left(2 - \sqrt{3} \right)}\right) \left(\pi + 2 i \log{\left(\sqrt{3} + 2 \right)}\right)}{144}$$
5*pi^2*(pi + 2*i*log(2 + sqrt(3)))*(pi + 2*i*log(2 - sqrt(3)))/144
Respuesta rápida [src]
     -5*pi
x1 = -----
       6  
$$x_{1} = - \frac{5 \pi}{6}$$
     -pi 
x2 = ----
      6  
$$x_{2} = - \frac{\pi}{6}$$
       pi        /      ___\
x3 = - -- - I*log\2 - \/ 3 /
       2                    
$$x_{3} = - \frac{\pi}{2} - i \log{\left(2 - \sqrt{3} \right)}$$
       pi        /      ___\
x4 = - -- - I*log\2 + \/ 3 /
       2                    
$$x_{4} = - \frac{\pi}{2} - i \log{\left(\sqrt{3} + 2 \right)}$$
x4 = -pi/2 - i*log(sqrt(3) + 2)
Respuesta numérica [src]
x1 = -8.90117918517108
x2 = -773.355391558687
x3 = -15.1843644923507
x4 = 18.3259571459405
x5 = 66.497044500984
x6 = 93.7241808320955
x7 = -57.0722665402146
x8 = -25.6563400043166
x9 = 56.025068989018
x10 = 47.6474885794452
x11 = -101.054563690472
x12 = -78.0162175641465
x13 = -52.8834763354282
x14 = 5.75958653158129
x15 = -82.2050077689329
x16 = 28.7979326579064
x17 = 81.1578102177363
x18 = 97.9129710368819
x19 = 62766.4032248461
x20 = -0.523598775598299
x21 = 68.5914396033772
x22 = -90.5825881785057
x23 = 43.4586983746588
x24 = 100.007366139275
x25 = -46.6002910282486
x26 = 30.8923277602996
x27 = 37.1755130674792
x28 = -63.3554518473942
x29 = -27.7507351067098
x30 = -34.0339204138894
x31 = -44.5058959258554
x32 = 79.0634151153431
x33 = 91.6297857297023
x34 = -65.4498469497874
x35 = 72.7802298081635
x36 = 60.2138591938044
x37 = -71.733032256967
x38 = -31.9395253114962
x39 = 53.9306738866248
x40 = 3.66519142918809
x41 = 22.5147473507269
x42 = 1455.08099738767
x43 = -84.2994028713261
x44 = -88.4881930761125
x45 = -40.317105721069
x46 = -69.6386371545737
x47 = -50.789081233035
x48 = -6.80678408277789
x49 = -19.3731546971371
x50 = 87.4409955249159
x51 = 16.2315620435473
x52 = -38.2227106186758
x53 = 62.3082542961976
x54 = -94.7713783832921
x55 = 238.237442897226
x56 = 49.7418836818384
x57 = 74.8746249105567
x58 = -96.8657734856853
x59 = 85.3466004225227
x60 = 12.0427718387609
x61 = -21.4675497995303
x62 = 231545.326946304
x63 = -59.1666616426078
x64 = -13.0899693899575
x65 = 198.443935951755
x66 = 41.3643032722656
x67 = 24.60914245312
x68 = 35.081117965086
x69 = -75.9218224617533
x70 = 9.94837673636768
x71 = -2.61799387799149
x71 = -2.61799387799149
Gráfico
cos(2*x)-5*sin(x)-3=0 la ecuación