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2*​cos(​2)*​(x-​1)+​4*​x^​2-​8*​x=y la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
                      2          
2*cos(2)*(x - 1) + 4*x  - 8*x = y
$$- 8 x + \left(4 x^{2} + \left(x - 1\right) 2 \cos{\left(2 \right)}\right) = y$$
Solución detallada
Transportemos el miembro derecho de la ecuación al
miembro izquierdo de la ecuación con el signo negativo.

La ecuación se convierte de
$$- 8 x + \left(4 x^{2} + \left(x - 1\right) 2 \cos{\left(2 \right)}\right) = y$$
en
$$- y + \left(- 8 x + \left(4 x^{2} + \left(x - 1\right) 2 \cos{\left(2 \right)}\right)\right) = 0$$
Abramos la expresión en la ecuación
$$- y + \left(- 8 x + \left(4 x^{2} + \left(x - 1\right) 2 \cos{\left(2 \right)}\right)\right) = 0$$
Obtenemos la ecuación cuadrática
$$4 x^{2} - 8 x + 2 x \cos{\left(2 \right)} - y - 2 \cos{\left(2 \right)} = 0$$
Es la ecuación de la forma
a*x^2 + b*x + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = 4$$
$$b = -8 + 2 \cos{\left(2 \right)}$$
$$c = - y - 2 \cos{\left(2 \right)}$$
, entonces
D = b^2 - 4 * a * c = 

(-8 + 2*cos(2))^2 - 4 * (4) * (-y - 2*cos(2)) = (-8 + 2*cos(2))^2 + 16*y + 32*cos(2)

La ecuación tiene dos raíces.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

o
$$x_{1} = \frac{\sqrt{16 y + 32 \cos{\left(2 \right)} + \left(-8 + 2 \cos{\left(2 \right)}\right)^{2}}}{8} - \frac{\cos{\left(2 \right)}}{4} + 1$$
$$x_{2} = - \frac{\sqrt{16 y + 32 \cos{\left(2 \right)} + \left(-8 + 2 \cos{\left(2 \right)}\right)^{2}}}{8} - \frac{\cos{\left(2 \right)}}{4} + 1$$
Gráfica
Respuesta rápida [src]
                      _______________________________________                                                     _______________________________________                                            
                     /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\
                  4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|
                  \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------|
         cos(2)                                                  \                  2                   /                                                    \                  2                   /
x1 = 1 - ------ - --------------------------------------------------------------------------------------- - -----------------------------------------------------------------------------------------
           4                                                 4                                                                                          4                                            
$$x_{1} = - \frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1$$
                      _______________________________________                                                     _______________________________________                                            
                     /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\
                  4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|
                  \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------|
         cos(2)                                                  \                  2                   /                                                    \                  2                   /
x2 = 1 - ------ + --------------------------------------------------------------------------------------- + -----------------------------------------------------------------------------------------
           4                                                 4                                                                                          4                                            
$$x_{2} = \frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} + \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1$$
x2 = i*((4*re(y) + cos(2)^2 + 16)^2 + 16*im(y)^2)^(1/4)*sin(atan2(4*im(y, 4*re(y) + cos(2)^2 + 16)/2)/4 + ((4*re(y) + cos(2)^2 + 16)^2 + 16*im(y)^2)^(1/4)*cos(atan2(4*im(y), 4*re(y) + cos(2)^2 + 16)/2)/4 - cos(2)/4 + 1)
Suma y producto de raíces [src]
suma
                 _______________________________________                                                     _______________________________________                                                                _______________________________________                                                     _______________________________________                                            
                /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\                   /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\
             4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|                4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|
             \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------|                \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------|
    cos(2)                                                  \                  2                   /                                                    \                  2                   /       cos(2)                                                  \                  2                   /                                                    \                  2                   /
1 - ------ - --------------------------------------------------------------------------------------- - ----------------------------------------------------------------------------------------- + 1 - ------ + --------------------------------------------------------------------------------------- + -----------------------------------------------------------------------------------------
      4                                                 4                                                                                          4                                                     4                                                 4                                                                                          4                                            
$$\left(- \frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1\right) + \left(\frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} + \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1\right)$$
=
    cos(2)
2 - ------
      2   
$$2 - \frac{\cos{\left(2 \right)}}{2}$$
producto
/                 _______________________________________                                                     _______________________________________                                            \ /                 _______________________________________                                                     _______________________________________                                            \
|                /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\| |                /                         2                 /     /                 2             \\        /                         2                 /     /                 2             \\|
|             4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|| |             4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     4 /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/||
|             \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------|| |             \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin|--------------------------------------||
|    cos(2)                                                  \                  2                   /                                                    \                  2                   /| |    cos(2)                                                  \                  2                   /                                                    \                  2                   /|
|1 - ------ - --------------------------------------------------------------------------------------- - -----------------------------------------------------------------------------------------|*|1 - ------ + --------------------------------------------------------------------------------------- + -----------------------------------------------------------------------------------------|
\      4                                                 4                                                                                          4                                            / \      4                                                 4                                                                                          4                                            /
$$\left(- \frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1\right) \left(\frac{i \sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} + \frac{\sqrt[4]{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{4} - \frac{\cos{\left(2 \right)}}{4} + 1\right)$$
=
                           _______________________________________                                                    _______________________________________                                                      _______________________________________                                                                                        
                          /                         2                  /     /                 2             \\      /                         2                  /     /                 2             \\        /                         2                 /     /                 2             \\    /     /                 2             \\
                         /  /        2             \         2        2|atan2\4*im(y), 16 + cos (2) + 4*re(y)/|     /  /        2             \         2        2|atan2\4*im(y), 16 + cos (2) + 4*re(y)/|       /  /        2             \         2        |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|    |atan2\4*im(y), 16 + cos (2) + 4*re(y)/|
                2      \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos |--------------------------------------|   \/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *sin |--------------------------------------|   I*\/   \16 + cos (2) + 4*re(y)/  + 16*im (y) *cos|--------------------------------------|*sin|--------------------------------------|
    cos(2)   cos (2)                                                   \                  2                   /                                                   \                  2                   /                                                    \                  2                   /    \                  2                   /
1 - ------ + ------- - ---------------------------------------------------------------------------------------- + ---------------------------------------------------------------------------------------- - -------------------------------------------------------------------------------------------------------------------------------------
      2         16                                                16                                                                                         16                                                                                                                8                                                                  
$$\frac{\sqrt{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin^{2}{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{16} - \frac{i \sqrt{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)} \cos{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{8} - \frac{\sqrt{\left(4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16\right)^{2} + 16 \left(\operatorname{im}{\left(y\right)}\right)^{2}} \cos^{2}{\left(\frac{\operatorname{atan_{2}}{\left(4 \operatorname{im}{\left(y\right)},4 \operatorname{re}{\left(y\right)} + \cos^{2}{\left(2 \right)} + 16 \right)}}{2} \right)}}{16} + \frac{\cos^{2}{\left(2 \right)}}{16} - \frac{\cos{\left(2 \right)}}{2} + 1$$
1 - cos(2)/2 + cos(2)^2/16 - sqrt((16 + cos(2)^2 + 4*re(y))^2 + 16*im(y)^2)*cos(atan2(4*im(y), 16 + cos(2)^2 + 4*re(y))/2)^2/16 + sqrt((16 + cos(2)^2 + 4*re(y))^2 + 16*im(y)^2)*sin(atan2(4*im(y), 16 + cos(2)^2 + 4*re(y))/2)^2/16 - i*sqrt((16 + cos(2)^2 + 4*re(y))^2 + 16*im(y)^2)*cos(atan2(4*im(y), 16 + cos(2)^2 + 4*re(y))/2)*sin(atan2(4*im(y), 16 + cos(2)^2 + 4*re(y))/2)/8