x^4-2*x^2+3=0 la ecuación
El profesor se sorprenderá mucho al ver tu solución correcta😉
Solución
Solución detallada
Tenemos la ecuación:
( x 4 − 2 x 2 ) + 3 = 0 \left(x^{4} - 2 x^{2}\right) + 3 = 0 ( x 4 − 2 x 2 ) + 3 = 0 Sustituimos
v = x 2 v = x^{2} v = x 2 entonces la ecuación será así:
v 2 − 2 v + 3 = 0 v^{2} - 2 v + 3 = 0 v 2 − 2 v + 3 = 0 Es la ecuación de la forma
a*v^2 + b*v + c = 0 La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
v 1 = D − b 2 a v_{1} = \frac{\sqrt{D} - b}{2 a} v 1 = 2 a D − b v 2 = − D − b 2 a v_{2} = \frac{- \sqrt{D} - b}{2 a} v 2 = 2 a − D − b donde D = b^2 - 4*a*c es el discriminante.
Como
a = 1 a = 1 a = 1 b = − 2 b = -2 b = − 2 c = 3 c = 3 c = 3 , entonces
D = b^2 - 4 * a * c = (-2)^2 - 4 * (1) * (3) = -8 Como D < 0 la ecuación
no tiene raíces reales,
pero hay raíces complejas.
v1 = (-b + sqrt(D)) / (2*a) v2 = (-b - sqrt(D)) / (2*a) o
v 1 = 1 + 2 i v_{1} = 1 + \sqrt{2} i v 1 = 1 + 2 i v 2 = 1 − 2 i v_{2} = 1 - \sqrt{2} i v 2 = 1 − 2 i Entonces la respuesta definitiva es:
Como
v = x 2 v = x^{2} v = x 2 entonces
x 1 = v 1 x_{1} = \sqrt{v_{1}} x 1 = v 1 x 2 = − v 1 x_{2} = - \sqrt{v_{1}} x 2 = − v 1 x 3 = v 2 x_{3} = \sqrt{v_{2}} x 3 = v 2 x 4 = − v 2 x_{4} = - \sqrt{v_{2}} x 4 = − v 2 entonces:
x 1 = x_{1} = x 1 = 0 1 + ( 1 + 2 i ) 1 2 1 = 1 + 2 i \frac{0}{1} + \frac{\left(1 + \sqrt{2} i\right)^{\frac{1}{2}}}{1} = \sqrt{1 + \sqrt{2} i} 1 0 + 1 ( 1 + 2 i ) 2 1 = 1 + 2 i x 2 = x_{2} = x 2 = 0 1 + ( − 1 ) ( 1 + 2 i ) 1 2 1 = − 1 + 2 i \frac{0}{1} + \frac{\left(-1\right) \left(1 + \sqrt{2} i\right)^{\frac{1}{2}}}{1} = - \sqrt{1 + \sqrt{2} i} 1 0 + 1 ( − 1 ) ( 1 + 2 i ) 2 1 = − 1 + 2 i x 3 = x_{3} = x 3 = 0 1 + ( 1 − 2 i ) 1 2 1 = 1 − 2 i \frac{0}{1} + \frac{\left(1 - \sqrt{2} i\right)^{\frac{1}{2}}}{1} = \sqrt{1 - \sqrt{2} i} 1 0 + 1 ( 1 − 2 i ) 2 1 = 1 − 2 i x 4 = x_{4} = x 4 = 0 1 + ( − 1 ) ( 1 − 2 i ) 1 2 1 = − 1 − 2 i \frac{0}{1} + \frac{\left(-1\right) \left(1 - \sqrt{2} i\right)^{\frac{1}{2}}}{1} = - \sqrt{1 - \sqrt{2} i} 1 0 + 1 ( − 1 ) ( 1 − 2 i ) 2 1 = − 1 − 2 i
Gráfica
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 20
/ / ___\\ / / ___\\
4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|
x1 = - \/ 3 *cos|-----------| - I*\/ 3 *sin|-----------|
\ 2 / \ 2 /
x 1 = − 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) x_{1} = - \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} x 1 = − 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) )
/ / ___\\ / / ___\\
4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|
x2 = - \/ 3 *cos|-----------| + I*\/ 3 *sin|-----------|
\ 2 / \ 2 /
x 2 = − 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) x_{2} = - \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} x 2 = − 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) )
/ / ___\\ / / ___\\
4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|
x3 = \/ 3 *cos|-----------| - I*\/ 3 *sin|-----------|
\ 2 / \ 2 /
x 3 = 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) x_{3} = \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} x 3 = 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) )
/ / ___\\ / / ___\\
4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|
x4 = \/ 3 *cos|-----------| + I*\/ 3 *sin|-----------|
\ 2 / \ 2 /
x 4 = 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) x_{4} = \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} x 4 = 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) )
x4 = 3^(1/4)*cos(atan(sqrt(2))/2) + 3^(1/4)*i*sin(atan(sqrt(2))/2)
Suma y producto de raíces
[src]
/ / ___\\ / / ___\\ / / ___\\ / / ___\\ / / ___\\ / / ___\\ / / ___\\ / / ___\\
4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|
- \/ 3 *cos|-----------| - I*\/ 3 *sin|-----------| + - \/ 3 *cos|-----------| + I*\/ 3 *sin|-----------| + \/ 3 *cos|-----------| - I*\/ 3 *sin|-----------| + \/ 3 *cos|-----------| + I*\/ 3 *sin|-----------|
\ 2 / \ 2 / \ 2 / \ 2 / \ 2 / \ 2 / \ 2 / \ 2 /
( ( 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) ) + ( ( − 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) ) + ( − 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) ) ) ) + ( 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) ) \left(\left(\sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) + \left(\left(- \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) + \left(- \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right)\right)\right) + \left(\sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) ( ( 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) ) ) + ( ( − 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) ) ) + ( − 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) ) ) ) ) + ( 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) ) )
/ / / ___\\ / / ___\\\ / / / ___\\ / / ___\\\ / / / ___\\ / / ___\\\ / / / ___\\ / / ___\\\
| 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|| | 4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|| |4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /|| |4 ___ |atan\\/ 2 /| 4 ___ |atan\\/ 2 /||
|- \/ 3 *cos|-----------| - I*\/ 3 *sin|-----------||*|- \/ 3 *cos|-----------| + I*\/ 3 *sin|-----------||*|\/ 3 *cos|-----------| - I*\/ 3 *sin|-----------||*|\/ 3 *cos|-----------| + I*\/ 3 *sin|-----------||
\ \ 2 / \ 2 // \ \ 2 / \ 2 // \ \ 2 / \ 2 // \ \ 2 / \ 2 //
( − 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) ) ( − 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) ) ( 3 4 cos ( atan ( 2 ) 2 ) − 3 4 i sin ( atan ( 2 ) 2 ) ) ( 3 4 cos ( atan ( 2 ) 2 ) + 3 4 i sin ( atan ( 2 ) 2 ) ) \left(- \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) \left(- \sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) \left(\sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} - \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) \left(\sqrt[4]{3} \cos{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)} + \sqrt[4]{3} i \sin{\left(\frac{\operatorname{atan}{\left(\sqrt{2} \right)}}{2} \right)}\right) ( − 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) ) ) ( − 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) ) ) ( 4 3 cos ( 2 atan ( 2 ) ) − 4 3 i sin ( 2 atan ( 2 ) ) ) ( 4 3 cos ( 2 atan ( 2 ) ) + 4 3 i sin ( 2 atan ( 2 ) ) )
x1 = -1.16877089448037 - 0.605000333706056*i
x2 = 1.16877089448037 + 0.605000333706056*i
x3 = -1.16877089448037 + 0.605000333706056*i
x4 = 1.16877089448037 - 0.605000333706056*i
x4 = 1.16877089448037 - 0.605000333706056*i