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2,5-sqrt(2)cos(x)+cos^2(x)=2 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
5     ___             2       
- - \/ 2 *cos(x) + cos (x) = 2
2                             
$$\left(- \sqrt{2} \cos{\left(x \right)} + \frac{5}{2}\right) + \cos^{2}{\left(x \right)} = 2$$
Solución detallada
Tenemos la ecuación
$$\left(- \sqrt{2} \cos{\left(x \right)} + \frac{5}{2}\right) + \cos^{2}{\left(x \right)} = 2$$
cambiamos
$$\cos^{2}{\left(x \right)} - \sqrt{2} \cos{\left(x \right)} + \frac{1}{2} = 0$$
$$\left(\left(- \sqrt{2} \cos{\left(x \right)} + \frac{5}{2}\right) + \cos^{2}{\left(x \right)}\right) - 2 = 0$$
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
$$a = 1$$
$$b = - \sqrt{2}$$
$$c = \frac{1}{2}$$
, entonces
D = b^2 - 4 * a * c = 

(-sqrt(2))^2 - 4 * (1) * (1/2) = 0

Como D = 0 hay sólo una raíz.
w = -b/2a = --sqrt(2)/2/(1)

$$w_{1} = \frac{\sqrt{2}}{2}$$
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:
$$x_{1} = \pi n + \operatorname{acos}{\left(w_{1} \right)}$$
$$x_{1} = \pi n + \operatorname{acos}{\left(\frac{\sqrt{2}}{2} \right)}$$
$$x_{1} = \pi n + \frac{\pi}{4}$$
$$x_{2} = \pi n + \operatorname{acos}{\left(w_{1} \right)} - \pi$$
$$x_{2} = \pi n - \pi + \operatorname{acos}{\left(\frac{\sqrt{2}}{2} \right)}$$
$$x_{2} = \pi n - \frac{3 \pi}{4}$$
Gráfica
Respuesta rápida [src]
     pi
x1 = --
     4 
$$x_{1} = \frac{\pi}{4}$$
     7*pi
x2 = ----
      4  
$$x_{2} = \frac{7 \pi}{4}$$
x2 = 7*pi/4
Suma y producto de raíces [src]
suma
pi   7*pi
-- + ----
4     4  
$$\frac{\pi}{4} + \frac{7 \pi}{4}$$
=
2*pi
$$2 \pi$$
producto
pi 7*pi
--*----
4   4  
$$\frac{\pi}{4} \frac{7 \pi}{4}$$
=
    2
7*pi 
-----
  16 
$$\frac{7 \pi^{2}}{16}$$
7*pi^2/16
Respuesta numérica [src]
x1 = -32.201325385796
x2 = 99.7455660105354
x3 = -68.3296399371994
x4 = 88.7499931634605
x5 = 5.49778642355736
x6 = 74.6128252586329
x7 = 124.878307230499
x8 = -57.3340662334586
x9 = -24.3473427727601
x10 = -18.0641576938177
x11 = 76.1836217708077
x12 = -38.4845108198065
x13 = -49.4800835352062
x14 = -19.6349541663612
x15 = 13.3517693090462
x16 = 43.196898290978
x17 = 44.7676961432743
x18 = 93.4623806381473
x19 = -44.7676960297012
x20 = 38.4845099221655
x21 = -74.6128250186588
x22 = -82.4668073509902
x23 = 38.4845107333964
x24 = -0.785398187593858
x25 = -24.3473432502031
x26 = -93.4623806722569
x27 = -62.0464548600946
x28 = 124.878309453203
x29 = -69.9004361978763
x30 = 62.0464549003508
x31 = 82.4668078646108
x32 = -43.1968981617486
x33 = -95.0331783108931
x34 = -93.462381528939
x35 = -55.7632695907522
x36 = 62.0464547968705
x37 = 55.7632688762055
x38 = -30.63052785475
x39 = -87.1791953152408
x40 = 25.9181394717794
x41 = 18.064157481074
x42 = -5.49778722914389
x43 = 24.3473429962931
x44 = -11.780972424191
x45 = 19.6349543917002
x46 = -76.1836225130438
x47 = -36.9137129668191
x48 = -25.9181392495517
x49 = 51.0508813535645
x50 = 36.913713180079
x51 = -49.4800853000426
x52 = 82.4668070742751
x53 = -11.7809723755497
x54 = -51.0508811473503
x55 = 7.06858419353762
x56 = -7.06858398368901
x57 = 95.0331785132461
x58 = -57.334065810609
x59 = 49.4800834847837
x60 = 5.49778633211921
x61 = -88.749993189531
x62 = -99.7455667547077
x63 = 80.8960103439421
x64 = 76.1836219229699
x65 = -0.785398869525843
x66 = 30.6305280946613
x67 = -32.2013246117462
x68 = 32.2013247462446
x69 = -63.61725132907
x70 = 11.7809717440281
x71 = -69.9004363376154
x72 = 69.9004366369124
x73 = 57.3340664727187
x74 = 88.7499932947387
x75 = 68.3296401589187
x76 = -99.7455665313592
x77 = 32.2013246976047
x78 = -80.8960101274907
x79 = 18.064157827358
x80 = -76.1836217642183
x81 = -38.4845103859399
x82 = 11.7809725400091
x83 = -55.7632694513641
x84 = 87.1791954517937
x85 = 55.7632696910239
x86 = -82.46680797095
x87 = 0.785398991100381
x88 = -5.49778639993542
x89 = 63.6172515561773
x90 = -49.4800843795575
x91 = 99.7455668412514
x92 = -13.3517690693718
x93 = -24.347341680222
x94 = -19.634955212871
x95 = -44.7676950778486
x95 = -44.7676950778486