Sr Examen

Otras calculadoras

sqrt(1)-sqrt(cos(x))=sqrt(2)*cos(x) la ecuación

El profesor se sorprenderá mucho al ver tu solución correcta😉

v

Solución numérica:

Buscar la solución numérica en el intervalo [, ]

Solución

Ha introducido [src]
  ___     ________     ___       
\/ 1  - \/ cos(x)  = \/ 2 *cos(x)
$$- \sqrt{\cos{\left(x \right)}} + \sqrt{1} = \sqrt{2} \cos{\left(x \right)}$$
Solución detallada
Tenemos la ecuación
$$- \sqrt{\cos{\left(x \right)}} + \sqrt{1} = \sqrt{2} \cos{\left(x \right)}$$
cambiamos
$$- \sqrt{\cos{\left(x \right)}} - \sqrt{2} \cos{\left(x \right)} + 1 = 0$$
$$\left(- \sqrt{\cos{\left(x \right)}} + \sqrt{1}\right) - \sqrt{2} \cos{\left(x \right)} = 0$$
Sustituimos
$$w = \cos{\left(x \right)}$$
$$- \sqrt{w} = \sqrt{2} w - 1$$
Elevemos las dos partes de la ecuación a la potencia 2
$$w = \left(\sqrt{2} w - 1\right)^{2}$$
$$w = 2 w^{2} - 2 \sqrt{2} w + 1$$
Transpongamos la parte derecha de la ecuación miembro izquierdo de la ecuación con el signo negativo
$$- 2 w^{2} + w + 2 \sqrt{2} w - 1 = 0$$
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
$$a = -2$$
$$b = 1 + 2 \sqrt{2}$$
$$c = -1$$
, entonces
D = b^2 - 4 * a * c = 

(1 + 2*sqrt(2))^2 - 4 * (-2) * (-1) = -8 + (1 + 2*sqrt(2))^2

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

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

o
$$w_{1} = - \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2}$$
$$w_{2} = \frac{1}{4} + \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{\sqrt{2}}{2}$$

Como
$$\sqrt{w} = - \sqrt{2} w + 1$$
y
$$\sqrt{w} \geq 0$$
entonces
$$- \sqrt{2} w + 1 \geq 0$$
o
$$-\infty < w$$
$$w \leq \frac{\sqrt{2}}{2}$$
Entonces la respuesta definitiva es:
$$w_{1} = - \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2}$$
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:
$$x_{1} = \pi n + \operatorname{acos}{\left(w_{1} \right)}$$
$$x_{1} = \pi n + \operatorname{acos}{\left(- \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
$$x_{1} = \pi n + \operatorname{acos}{\left(- \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
$$x_{2} = \pi n + \operatorname{acos}{\left(w_{1} \right)} - \pi$$
$$x_{2} = \pi n - \pi + \operatorname{acos}{\left(- \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
$$x_{2} = \pi n - \pi + \operatorname{acos}{\left(- \frac{\sqrt{-8 + \left(1 + 2 \sqrt{2}\right)^{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
Gráfica
Respuesta rápida [src]
         /               _____________\
         |      ___     /         ___ |
         |1   \/ 2    \/  1 + 4*\/ 2  |
x1 = acos|- + ----- - ----------------|
         \4     2            4        /
$$x_{1} = \operatorname{acos}{\left(- \frac{\sqrt{1 + 4 \sqrt{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
x1 = acos(-sqrt(1 + 4*sqrt(2))/4 + 1/4 + sqrt(2)/2)
Suma y producto de raíces [src]
suma
    /               _____________\
    |      ___     /         ___ |
    |1   \/ 2    \/  1 + 4*\/ 2  |
acos|- + ----- - ----------------|
    \4     2            4        /
$$\operatorname{acos}{\left(- \frac{\sqrt{1 + 4 \sqrt{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
=
    /               _____________\
    |      ___     /         ___ |
    |1   \/ 2    \/  1 + 4*\/ 2  |
acos|- + ----- - ----------------|
    \4     2            4        /
$$\operatorname{acos}{\left(- \frac{\sqrt{1 + 4 \sqrt{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
producto
    /               _____________\
    |      ___     /         ___ |
    |1   \/ 2    \/  1 + 4*\/ 2  |
acos|- + ----- - ----------------|
    \4     2            4        /
$$\operatorname{acos}{\left(- \frac{\sqrt{1 + 4 \sqrt{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
=
    /               _____________\
    |      ___     /         ___ |
    |1   \/ 2    \/  1 + 4*\/ 2  |
acos|- + ----- - ----------------|
    \4     2            4        /
$$\operatorname{acos}{\left(- \frac{\sqrt{1 + 4 \sqrt{2}}}{4} + \frac{1}{4} + \frac{\sqrt{2}}{2} \right)}$$
acos(1/4 + sqrt(2)/2 - sqrt(1 + 4*sqrt(2))/4)
Respuesta numérica [src]
x1 = 95.501189317675
x2 = 11.312960904378
x3 = -99.2775552048922
x4 = 36.4457021330963
x5 = 86.711184590533
x6 = -64.0852627817771
x7 = 1.25340970998119
x8 = -82.9348187033158
x9 = 74.1448139761739
x10 = 80.4279992833534
x11 = -51.5188921674179
x12 = 64.0852627817771
x13 = 99.2775552048922
x14 = -38.9525215530587
x15 = 57.8020774745975
x16 = -76.6516333961362
x17 = 42.7288874402759
x18 = -42.7288874402759
x19 = 20.10296563152
x20 = -74.1448139761739
x21 = -7.53659501716078
x22 = 92.9943698977126
x23 = -70.3684480889566
x24 = 61.5784433618147
x25 = -17.5961462115576
x26 = -92.9943698977126
x27 = 49.0120727474555
x28 = 30.1625168259167
x29 = 45.2357068602383
x30 = -101.784374624855
x31 = 51.5188921674179
x32 = 67.8616286689943
x33 = 55.2952580546351
x34 = -13.8197803243404
x35 = 82.9348187033158
x36 = 17.5961462115576
x37 = 76.6516333961362
x38 = -49.0120727474555
x39 = -95.501189317675
x40 = -32.6693362458791
x41 = -20.10296563152
x42 = 70.3684480889566
x43 = 23.8793315187372
x44 = -36.4457021330963
x45 = -80.4279992833534
x46 = -86.711184590533
x47 = -23.8793315187372
x48 = -30.1625168259167
x49 = 7.53659501716078
x50 = -26.3861509386995
x51 = -89.2180040104954
x52 = 133.200301160753
x53 = 13.8197803243404
x54 = -55.2952580546351
x55 = 32.6693362458791
x56 = -57.8020774745975
x57 = -5.02977559719839
x58 = -1.25340970998119
x59 = -67.8616286689943
x60 = 5.02977559719839
x61 = 89.2180040104954
x62 = -45.2357068602383
x63 = -11.312960904378
x64 = -155.826222969508
x65 = 26.3861509386995
x66 = 38.9525215530587
x67 = -61.5784433618147
x68 = -258.864007304344
x68 = -258.864007304344