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1-2sin^2x=-3/2 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
         2          
1 - 2*sin (x) = -3/2
$$1 - 2 \sin^{2}{\left(x \right)} = - \frac{3}{2}$$
Solución detallada
Tenemos la ecuación
$$1 - 2 \sin^{2}{\left(x \right)} = - \frac{3}{2}$$
cambiamos
$$\cos{\left(2 x \right)} + \frac{3}{2} = 0$$
$$\left(1 - 2 \sin^{2}{\left(x \right)}\right) + \frac{3}{2} = 0$$
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
$$a = -2$$
$$b = 0$$
$$c = \frac{5}{2}$$
, entonces
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (-2) * (5/2) = 20

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

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

o
$$w_{1} = - \frac{\sqrt{5}}{2}$$
$$w_{2} = \frac{\sqrt{5}}{2}$$
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:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(- \frac{\sqrt{5}}{2} \right)}$$
$$x_{1} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n + \pi - \operatorname{asin}{\left(- \frac{\sqrt{5}}{2} \right)}$$
$$x_{3} = 2 \pi n + \pi + \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}$$
Gráfica
Suma y producto de raíces [src]
suma
       /    /  ___\\       /    /  ___\\            /    /  ___\\     /    /  ___\\       /    /  ___\\       /    /  ___\\       /    /  ___\\     /    /  ___\\
       |    |\/ 5 ||       |    |\/ 5 ||            |    |\/ 5 ||     |    |\/ 5 ||       |    |\/ 5 ||       |    |\/ 5 ||       |    |\/ 5 ||     |    |\/ 5 ||
pi - re|asin|-----|| - I*im|asin|-----|| + pi + I*im|asin|-----|| + re|asin|-----|| + - re|asin|-----|| - I*im|asin|-----|| + I*im|asin|-----|| + re|asin|-----||
       \    \  2  //       \    \  2  //            \    \  2  //     \    \  2  //       \    \  2  //       \    \  2  //       \    \  2  //     \    \  2  //
$$\left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) + \left(\left(\left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) + \left(- \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right)\right) + \left(- \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right)\right)$$
=
2*pi
$$2 \pi$$
producto
/       /    /  ___\\       /    /  ___\\\ /         /    /  ___\\     /    /  ___\\\ /    /    /  ___\\       /    /  ___\\\ /    /    /  ___\\     /    /  ___\\\
|       |    |\/ 5 ||       |    |\/ 5 ||| |         |    |\/ 5 ||     |    |\/ 5 ||| |    |    |\/ 5 ||       |    |\/ 5 ||| |    |    |\/ 5 ||     |    |\/ 5 |||
|pi - re|asin|-----|| - I*im|asin|-----|||*|pi + I*im|asin|-----|| + re|asin|-----|||*|- re|asin|-----|| - I*im|asin|-----|||*|I*im|asin|-----|| + re|asin|-----|||
\       \    \  2  //       \    \  2  /// \         \    \  2  //     \    \  2  /// \    \    \  2  //       \    \  2  /// \    \    \  2  //     \    \  2  ///
$$\left(- \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) \left(- \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right)$$
=
                                     2                                                                                       
/    /    /  ___\\     /    /  ___\\\  /         /    /  ___\\     /    /  ___\\\ /          /    /  ___\\     /    /  ___\\\
|    |    |\/ 5 ||     |    |\/ 5 |||  |         |    |\/ 5 ||     |    |\/ 5 ||| |          |    |\/ 5 ||     |    |\/ 5 |||
|I*im|asin|-----|| + re|asin|-----||| *|pi + I*im|asin|-----|| + re|asin|-----|||*|-pi + I*im|asin|-----|| + re|asin|-----|||
\    \    \  2  //     \    \  2  ///  \         \    \  2  //     \    \  2  /// \          \    \  2  //     \    \  2  ///
$$\left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right)^{2} \left(- \pi + \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}\right)$$
(i*im(asin(sqrt(5)/2)) + re(asin(sqrt(5)/2)))^2*(pi + i*im(asin(sqrt(5)/2)) + re(asin(sqrt(5)/2)))*(-pi + i*im(asin(sqrt(5)/2)) + re(asin(sqrt(5)/2)))
Respuesta rápida [src]
            /    /  ___\\       /    /  ___\\
            |    |\/ 5 ||       |    |\/ 5 ||
x1 = pi - re|asin|-----|| - I*im|asin|-----||
            \    \  2  //       \    \  2  //
$$x_{1} = - \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}$$
              /    /  ___\\     /    /  ___\\
              |    |\/ 5 ||     |    |\/ 5 ||
x2 = pi + I*im|asin|-----|| + re|asin|-----||
              \    \  2  //     \    \  2  //
$$x_{2} = \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + \pi + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}$$
         /    /  ___\\       /    /  ___\\
         |    |\/ 5 ||       |    |\/ 5 ||
x3 = - re|asin|-----|| - I*im|asin|-----||
         \    \  2  //       \    \  2  //
$$x_{3} = - \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} - i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}$$
         /    /  ___\\     /    /  ___\\
         |    |\/ 5 ||     |    |\/ 5 ||
x4 = I*im|asin|-----|| + re|asin|-----||
         \    \  2  //     \    \  2  //
$$x_{4} = \operatorname{re}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{asin}{\left(\frac{\sqrt{5}}{2} \right)}\right)}$$
x4 = re(asin(sqrt(5)/2)) + i*im(asin(sqrt(5)/2))
Respuesta numérica [src]
x1 = 1.5707963267949 + 0.481211825059603*i
x2 = 4.71238898038469 - 0.481211825059603*i
x3 = -1.5707963267949 + 0.481211825059603*i
x4 = 1.5707963267949 - 0.481211825059603*i
x4 = 1.5707963267949 - 0.481211825059603*i