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10*cos^2(x)+3*cos(x)-1=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
      2                      
10*cos (x) + 3*cos(x) - 1 = 0
$$\left(10 \cos^{2}{\left(x \right)} + 3 \cos{\left(x \right)}\right) - 1 = 0$$
Solución detallada
Tenemos la ecuación
$$\left(10 \cos^{2}{\left(x \right)} + 3 \cos{\left(x \right)}\right) - 1 = 0$$
cambiamos
$$10 \cos^{2}{\left(x \right)} + 3 \cos{\left(x \right)} - 1 = 0$$
$$\left(10 \cos^{2}{\left(x \right)} + 3 \cos{\left(x \right)}\right) - 1 = 0$$
Sustituimos
$$w = \cos{\left(x \right)}$$
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
$$a = 10$$
$$b = 3$$
$$c = -1$$
, entonces
D = b^2 - 4 * a * c = 

(3)^2 - 4 * (10) * (-1) = 49

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

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

o
$$w_{1} = \frac{1}{5}$$
$$w_{2} = - \frac{1}{2}$$
hacemos cambio inverso
$$\cos{\left(x \right)} = w$$
Tenemos la ecuación
$$\cos{\left(x \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$x = \pi n + \operatorname{acos}{\left(w \right)}$$
$$x = \pi n + \operatorname{acos}{\left(w \right)} - \pi$$
O
$$x = \pi n + \operatorname{acos}{\left(w \right)}$$
$$x = \pi n + \operatorname{acos}{\left(w \right)} - \pi$$
, donde n es cualquier número entero
sustituimos w:
$$x_{1} = \pi n + \operatorname{acos}{\left(w_{1} \right)}$$
$$x_{1} = \pi n + \operatorname{acos}{\left(\frac{1}{5} \right)}$$
$$x_{1} = \pi n + \operatorname{acos}{\left(\frac{1}{5} \right)}$$
$$x_{2} = \pi n + \operatorname{acos}{\left(w_{2} \right)}$$
$$x_{2} = \pi n + \operatorname{acos}{\left(- \frac{1}{2} \right)}$$
$$x_{2} = \pi n + \frac{2 \pi}{3}$$
$$x_{3} = \pi n + \operatorname{acos}{\left(w_{1} \right)} - \pi$$
$$x_{3} = \pi n - \pi + \operatorname{acos}{\left(\frac{1}{5} \right)}$$
$$x_{3} = \pi n - \pi + \operatorname{acos}{\left(\frac{1}{5} \right)}$$
$$x_{4} = \pi n + \operatorname{acos}{\left(w_{2} \right)} - \pi$$
$$x_{4} = \pi n - \pi + \operatorname{acos}{\left(- \frac{1}{2} \right)}$$
$$x_{4} = \pi n - \frac{\pi}{3}$$
Gráfica
Suma y producto de raíces [src]
suma
2*pi   4*pi                                
---- + ---- + -acos(1/5) + 2*pi + acos(1/5)
 3      3                                  
$$\operatorname{acos}{\left(\frac{1}{5} \right)} + \left(\left(- \operatorname{acos}{\left(\frac{1}{5} \right)} + 2 \pi\right) + \left(\frac{2 \pi}{3} + \frac{4 \pi}{3}\right)\right)$$
=
4*pi
$$4 \pi$$
producto
2*pi 4*pi                              
----*----*(-acos(1/5) + 2*pi)*acos(1/5)
 3    3                                
$$\frac{2 \pi}{3} \frac{4 \pi}{3} \left(- \operatorname{acos}{\left(\frac{1}{5} \right)} + 2 \pi\right) \operatorname{acos}{\left(\frac{1}{5} \right)}$$
=
    2                              
8*pi *(-acos(1/5) + 2*pi)*acos(1/5)
-----------------------------------
                 9                 
$$\frac{8 \pi^{2} \left(- \operatorname{acos}{\left(\frac{1}{5} \right)} + 2 \pi\right) \operatorname{acos}{\left(\frac{1}{5} \right)}}{9}$$
8*pi^2*(-acos(1/5) + 2*pi)*acos(1/5)/9
Respuesta rápida [src]
     2*pi
x1 = ----
      3  
$$x_{1} = \frac{2 \pi}{3}$$
     4*pi
x2 = ----
      3  
$$x_{2} = \frac{4 \pi}{3}$$
x3 = -acos(1/5) + 2*pi
$$x_{3} = - \operatorname{acos}{\left(\frac{1}{5} \right)} + 2 \pi$$
x4 = acos(1/5)
$$x_{4} = \operatorname{acos}{\left(\frac{1}{5} \right)}$$
x4 = acos(1/5)
Respuesta numérica [src]
x1 = 32.7853649419025
x2 = 60.7374579694027
x3 = -98.4365698124802
x4 = 39.0685502490821
x5 = 64.2012914778004
x6 = -17.4801175155342
x7 = -83.7758040957278
x8 = -71.2094334813686
x9 = 23.7633028227138
x10 = -48.8960440514321
x11 = 36.329673437073
x12 = 46.0766922526503
x13 = 99.1615265088688
x14 = -46.0766922526503
x15 = 30.0464881298934
x16 = -35.6047167406843
x17 = -92.8783412016892
x18 = 16.7551608191456
x19 = -20.2189943275433
x20 = 98.4365698124802
x21 = -7.65262371318415
x22 = -74.0287852801505
x23 = 39.7935069454707
x24 = 4.18879020478639
x25 = -95.6172180136984
x26 = -32.7853649419025
x27 = -57.9181061706208
x28 = 13.9358090203637
x29 = -85.870199198121
x30 = 17.4801175155342
x31 = -4.91374690117502
x32 = -99.1615265088688
x33 = 96.342174710087
x34 = -90.0589894029074
x35 = -64.2012914778004
x36 = 85.870199198121
x37 = 4.91374690117502
x38 = 52.3598775598299
x39 = -70.48447678498
x40 = -39.0685502490821
x41 = 174.559750195024
x42 = -4.18879020478639
x43 = 10.471975511966
x44 = -61.4624146657913
x45 = -104.71975511966
x46 = 54.4542726622231
x47 = 42.6128587442525
x48 = 7.65262371318415
x49 = 57.9181061706208
x50 = 45.3517355562617
x51 = 83.0508473993392
x52 = -86.5951558945096
x53 = 61.4624146657913
x54 = -2.0943951023932
x55 = -92.1533845053006
x56 = 41.8879020478639
x57 = 397.210112758319
x58 = -77.4926187885482
x59 = 76.7676620921596
x60 = -23.7633028227138
x61 = -55.1792293586117
x62 = -54.4542726622231
x63 = 20.2189943275433
x64 = 48.1710873550435
x65 = -51.6349208634413
x66 = -10.471975511966
x67 = 83.7758040957278
x68 = -76.7676620921596
x69 = -48.1710873550435
x70 = 11.1969322083546
x71 = -67.7455999729709
x72 = -11.1969322083546
x73 = -13.9358090203637
x74 = 80.3119705873301
x75 = 92.1533845053006
x76 = -41.8879020478639
x77 = 55.1792293586117
x78 = -33.5103216382911
x79 = 77.4926187885482
x80 = -27.2271363311115
x81 = 67.7455999729709
x82 = -26.5021796347229
x83 = 8.37758040957278
x84 = -79.5870138909414
x85 = 74.0287852801505
x86 = 33.5103216382911
x87 = -30.0464881298934
x88 = 70.48447678498
x89 = -39.7935069454707
x90 = 2.0943951023932
x91 = 90.0589894029074
x92 = 26.5021796347229
x92 = 26.5021796347229