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2*cos^2(x)+sin(x)+1=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
     2                    
2*cos (x) + sin(x) + 1 = 0
$$\left(\sin{\left(x \right)} + 2 \cos^{2}{\left(x \right)}\right) + 1 = 0$$
Solución detallada
Tenemos la ecuación
$$\left(\sin{\left(x \right)} + 2 \cos^{2}{\left(x \right)}\right) + 1 = 0$$
cambiamos
$$\sin{\left(x \right)} + \cos{\left(2 x \right)} + 2 = 0$$
$$- 2 \sin^{2}{\left(x \right)} + \sin{\left(x \right)} + 3 = 0$$
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
$$a = -2$$
$$b = 1$$
$$c = 3$$
, entonces
D = b^2 - 4 * a * c = 

(1)^2 - 4 * (-2) * (3) = 25

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

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

o
$$w_{1} = -1$$
$$w_{2} = \frac{3}{2}$$
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:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(-1 \right)}$$
$$x_{1} = 2 \pi n - \frac{\pi}{2}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{3}{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{3}{2} \right)}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(-1 \right)} + \pi$$
$$x_{3} = 2 \pi n + \frac{3 \pi}{2}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{3}{2} \right)}$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{3}{2} \right)}$$
Gráfica
Respuesta rápida [src]
     -pi 
x1 = ----
      2  
$$x_{1} = - \frac{\pi}{2}$$
         /    /        ___\\         /    /        ___\\
         |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||
x2 = 2*re|atan|- - -------|| + 2*I*im|atan|- - -------||
         \    \3      3   //         \    \3      3   //
$$x_{2} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)}$$
         /    /        ___\\         /    /        ___\\
         |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||
x3 = 2*re|atan|- + -------|| + 2*I*im|atan|- + -------||
         \    \3      3   //         \    \3      3   //
$$x_{3} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)}$$
x3 = 2*re(atan(2/3 + sqrt(5)*i/3)) + 2*i*im(atan(2/3 + sqrt(5)*i/3))
Suma y producto de raíces [src]
suma
           /    /        ___\\         /    /        ___\\       /    /        ___\\         /    /        ___\\
  pi       |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||       |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||
- -- + 2*re|atan|- - -------|| + 2*I*im|atan|- - -------|| + 2*re|atan|- + -------|| + 2*I*im|atan|- + -------||
  2        \    \3      3   //         \    \3      3   //       \    \3      3   //         \    \3      3   //
$$\left(- \frac{\pi}{2} + \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)}\right)\right) + \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)}\right)$$
=
    /    /        ___\\       /    /        ___\\              /    /        ___\\         /    /        ___\\
    |    |2   I*\/ 5 ||       |    |2   I*\/ 5 ||   pi         |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||
2*re|atan|- - -------|| + 2*re|atan|- + -------|| - -- + 2*I*im|atan|- - -------|| + 2*I*im|atan|- + -------||
    \    \3      3   //       \    \3      3   //   2          \    \3      3   //         \    \3      3   //
$$- \frac{\pi}{2} + 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)}$$
producto
     /    /    /        ___\\         /    /        ___\\\ /    /    /        ___\\         /    /        ___\\\
-pi  |    |    |2   I*\/ 5 ||         |    |2   I*\/ 5 ||| |    |    |2   I*\/ 5 ||         |    |2   I*\/ 5 |||
----*|2*re|atan|- - -------|| + 2*I*im|atan|- - -------|||*|2*re|atan|- + -------|| + 2*I*im|atan|- + -------|||
 2   \    \    \3      3   //         \    \3      3   /// \    \    \3      3   //         \    \3      3   ///
$$- \frac{\pi}{2} \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)}\right) \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)}\right)$$
=
      /    /    /        ___\\     /    /        ___\\\ /    /    /        ___\\     /    /        ___\\\
      |    |    |2   I*\/ 5 ||     |    |2   I*\/ 5 ||| |    |    |2   I*\/ 5 ||     |    |2   I*\/ 5 |||
-2*pi*|I*im|atan|- - -------|| + re|atan|- - -------|||*|I*im|atan|- + -------|| + re|atan|- + -------|||
      \    \    \3      3   //     \    \3      3   /// \    \    \3      3   //     \    \3      3   ///
$$- 2 \pi \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} - \frac{\sqrt{5} i}{3} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{2}{3} + \frac{\sqrt{5} i}{3} \right)}\right)}\right)$$
-2*pi*(i*im(atan(2/3 - i*sqrt(5)/3)) + re(atan(2/3 - i*sqrt(5)/3)))*(i*im(atan(2/3 + i*sqrt(5)/3)) + re(atan(2/3 + i*sqrt(5)/3)))
Respuesta numérica [src]
x1 = -139.800873249665
x2 = -14.1371668388268
x3 = -89.535390747472
x4 = 36.1283156694962
x5 = -76.9690202883133
x6 = 4.71238876303057
x7 = -70.6858348853437
x8 = 67.5442425428501
x9 = 92.676983075166
x10 = 92.6769826279201
x11 = -95.8185758681129
x12 = -20.420352026649
x13 = 17.2787593859766
x14 = -39.2699083927222
x15 = 48.6946859189952
x16 = 86.3937984757401
x17 = 98.9601687890347
x18 = 48.6946855745421
x19 = 23.5619454986408
x20 = -83.2522052663543
x21 = 29.8451303209123
x22 = 67.5442422847282
x23 = 86.3937983369643
x24 = -83.2522055482568
x25 = 54.9778716517999
x26 = 4.71238853044362
x27 = 42.4115007288249
x28 = 73.8274274802772
x29 = -32.9867231376832
x30 = -76.969019769254
x31 = -58.119464161524
x32 = -20.4203515680363
x33 = -64.402649182671
x34 = 23.5619451291519
x35 = -7.85398149817977
x36 = -83.2522055805072
x37 = -51.8362786896646
x38 = 4087901.62190845
x39 = 61.2610565245164
x40 = 86.3937978948071
x41 = -26.7035372754773
x42 = -14.1371675548369
x43 = -39.2699085196455
x44 = 10.9955745128692
x45 = -102.101761152532
x46 = -32.9867226275421
x47 = 61.2610570268883
x48 = 54.9778711648428
x49 = -70.6858349737007
x50 = -1.57079643014235
x51 = 86.3937978880117
x52 = -45.5530935889045
x53 = 10.9955740133772
x54 = 98.9601683166916
x55 = -58.1194639990021
x56 = 17.278759875892
x57 = -70.6858344272025
x58 = -1.57079608708683
x59 = -26.703537750735
x60 = -64.4026487407202
x61 = 80.1106131421182
x61 = 80.1106131421182