6x^3+3sqrt(2)*x^2-6*x+2sqrt(2)=0 la ecuación
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Solución
Teorema de Cardano-Vieta
reescribamos la ecuación
( − 6 x + ( 6 x 3 + 3 2 x 2 ) ) + 2 2 = 0 \left(- 6 x + \left(6 x^{3} + 3 \sqrt{2} x^{2}\right)\right) + 2 \sqrt{2} = 0 ( − 6 x + ( 6 x 3 + 3 2 x 2 ) ) + 2 2 = 0 de
a x 3 + b x 2 + c x + d = 0 a x^{3} + b x^{2} + c x + d = 0 a x 3 + b x 2 + c x + d = 0 como ecuación cúbica reducida
x 3 + b x 2 a + c x a + d a = 0 x^{3} + \frac{b x^{2}}{a} + \frac{c x}{a} + \frac{d}{a} = 0 x 3 + a b x 2 + a c x + a d = 0 x 3 + 2 x 2 2 − x + 2 3 = 0 x^{3} + \frac{\sqrt{2} x^{2}}{2} - x + \frac{\sqrt{2}}{3} = 0 x 3 + 2 2 x 2 − x + 3 2 = 0 p x 2 + q x + v + x 3 = 0 p x^{2} + q x + v + x^{3} = 0 p x 2 + q x + v + x 3 = 0 donde
p = b a p = \frac{b}{a} p = a b p = 2 2 p = \frac{\sqrt{2}}{2} p = 2 2 q = c a q = \frac{c}{a} q = a c q = − 1 q = -1 q = − 1 v = d a v = \frac{d}{a} v = a d v = 2 3 v = \frac{\sqrt{2}}{3} v = 3 2 Fórmulas de Cardano-Vieta
x 1 + x 2 + x 3 = − p x_{1} + x_{2} + x_{3} = - p x 1 + x 2 + x 3 = − p x 1 x 2 + x 1 x 3 + x 2 x 3 = q x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q x 1 x 2 + x 1 x 3 + x 2 x 3 = q x 1 x 2 x 3 = v x_{1} x_{2} x_{3} = v x 1 x 2 x 3 = v x 1 + x 2 + x 3 = − 2 2 x_{1} + x_{2} + x_{3} = - \frac{\sqrt{2}}{2} x 1 + x 2 + x 3 = − 2 2 x 1 x 2 + x 1 x 3 + x 2 x 3 = − 1 x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = -1 x 1 x 2 + x 1 x 3 + x 2 x 3 = − 1 x 1 x 2 x 3 = 2 3 x_{1} x_{2} x_{3} = \frac{\sqrt{2}}{3} x 1 x 2 x 3 = 3 2
Gráfica
-15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 7.5 10.0 12.5 -10000 10000
___ / ___ 3 ___ ___ 2/3\ ___ 3 ___ ___ 2/3
\/ 2 | \/ 6 *\/ 7 \/ 6 *7 | \/ 2 *\/ 7 \/ 2 *7
x1 = - ----- + I*|- ----------- + ----------| + ----------- + ----------
6 \ 12 12 / 12 12
x 1 = − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 7 3 12 + 6 ⋅ 7 2 3 12 ) x_{1} = - \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \sqrt[3]{7}}{12} + \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12}\right) x 1 = − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 3 7 + 12 6 ⋅ 7 3 2 )
___ / ___ 2/3 ___ 3 ___\ ___ 3 ___ ___ 2/3
\/ 2 | \/ 6 *7 \/ 6 *\/ 7 | \/ 2 *\/ 7 \/ 2 *7
x2 = - ----- + I*|- ---------- + -----------| + ----------- + ----------
6 \ 12 12 / 12 12
x 2 = − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 ⋅ 7 2 3 12 + 6 7 3 12 ) x_{2} = - \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12} + \frac{\sqrt{6} \sqrt[3]{7}}{12}\right) x 2 = − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 ⋅ 7 3 2 + 12 6 3 7 )
___ ___ 3 ___ ___ 2/3
\/ 2 \/ 2 *\/ 7 \/ 2 *4*7
x3 = - ----- - ----------- - ------------
6 6 24
x 3 = − 2 ⋅ 4 ⋅ 7 2 3 24 − 2 7 3 6 − 2 6 x_{3} = - \frac{\sqrt{2} \cdot 4 \cdot 7^{\frac{2}{3}}}{24} - \frac{\sqrt{2} \sqrt[3]{7}}{6} - \frac{\sqrt{2}}{6} x 3 = − 24 2 ⋅ 4 ⋅ 7 3 2 − 6 2 3 7 − 6 2
x3 = -sqrt(2)*4*7^(2/3)/24 - sqrt(2)*7^(1/3)/6 - sqrt(2)/6
Suma y producto de raíces
[src]
___ / ___ 3 ___ ___ 2/3\ ___ 3 ___ ___ 2/3 ___ / ___ 2/3 ___ 3 ___\ ___ 3 ___ ___ 2/3 ___ ___ 3 ___ ___ 2/3
\/ 2 | \/ 6 *\/ 7 \/ 6 *7 | \/ 2 *\/ 7 \/ 2 *7 \/ 2 | \/ 6 *7 \/ 6 *\/ 7 | \/ 2 *\/ 7 \/ 2 *7 \/ 2 \/ 2 *\/ 7 \/ 2 *4*7
- ----- + I*|- ----------- + ----------| + ----------- + ---------- + - ----- + I*|- ---------- + -----------| + ----------- + ---------- + - ----- - ----------- - ------------
6 \ 12 12 / 12 12 6 \ 12 12 / 12 12 6 6 24
( − 2 ⋅ 4 ⋅ 7 2 3 24 − 2 7 3 6 − 2 6 ) + ( ( − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 ⋅ 7 2 3 12 + 6 7 3 12 ) ) + ( − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 7 3 12 + 6 ⋅ 7 2 3 12 ) ) ) \left(- \frac{\sqrt{2} \cdot 4 \cdot 7^{\frac{2}{3}}}{24} - \frac{\sqrt{2} \sqrt[3]{7}}{6} - \frac{\sqrt{2}}{6}\right) + \left(\left(- \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12} + \frac{\sqrt{6} \sqrt[3]{7}}{12}\right)\right) + \left(- \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \sqrt[3]{7}}{12} + \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12}\right)\right)\right) ( − 24 2 ⋅ 4 ⋅ 7 3 2 − 6 2 3 7 − 6 2 ) + ( ( − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 ⋅ 7 3 2 + 12 6 3 7 ) ) + ( − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 3 7 + 12 6 ⋅ 7 3 2 ) ) )
___ / ___ 3 ___ ___ 2/3\ / ___ 2/3 ___ 3 ___\
\/ 2 | \/ 6 *\/ 7 \/ 6 *7 | | \/ 6 *7 \/ 6 *\/ 7 |
- ----- + I*|- ----------- + ----------| + I*|- ---------- + -----------|
2 \ 12 12 / \ 12 12 /
− 2 2 + i ( − 6 ⋅ 7 2 3 12 + 6 7 3 12 ) + i ( − 6 7 3 12 + 6 ⋅ 7 2 3 12 ) - \frac{\sqrt{2}}{2} + i \left(- \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12} + \frac{\sqrt{6} \sqrt[3]{7}}{12}\right) + i \left(- \frac{\sqrt{6} \sqrt[3]{7}}{12} + \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12}\right) − 2 2 + i ( − 12 6 ⋅ 7 3 2 + 12 6 3 7 ) + i ( − 12 6 3 7 + 12 6 ⋅ 7 3 2 )
/ ___ / ___ 3 ___ ___ 2/3\ ___ 3 ___ ___ 2/3\ / ___ / ___ 2/3 ___ 3 ___\ ___ 3 ___ ___ 2/3\ / ___ ___ 3 ___ ___ 2/3\
| \/ 2 | \/ 6 *\/ 7 \/ 6 *7 | \/ 2 *\/ 7 \/ 2 *7 | | \/ 2 | \/ 6 *7 \/ 6 *\/ 7 | \/ 2 *\/ 7 \/ 2 *7 | | \/ 2 \/ 2 *\/ 7 \/ 2 *4*7 |
|- ----- + I*|- ----------- + ----------| + ----------- + ----------|*|- ----- + I*|- ---------- + -----------| + ----------- + ----------|*|- ----- - ----------- - ------------|
\ 6 \ 12 12 / 12 12 / \ 6 \ 12 12 / 12 12 / \ 6 6 24 /
( − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 7 3 12 + 6 ⋅ 7 2 3 12 ) ) ( − 2 6 + 2 7 3 12 + 2 ⋅ 7 2 3 12 + i ( − 6 ⋅ 7 2 3 12 + 6 7 3 12 ) ) ( − 2 ⋅ 4 ⋅ 7 2 3 24 − 2 7 3 6 − 2 6 ) \left(- \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \sqrt[3]{7}}{12} + \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12}\right)\right) \left(- \frac{\sqrt{2}}{6} + \frac{\sqrt{2} \sqrt[3]{7}}{12} + \frac{\sqrt{2} \cdot 7^{\frac{2}{3}}}{12} + i \left(- \frac{\sqrt{6} \cdot 7^{\frac{2}{3}}}{12} + \frac{\sqrt{6} \sqrt[3]{7}}{12}\right)\right) \left(- \frac{\sqrt{2} \cdot 4 \cdot 7^{\frac{2}{3}}}{24} - \frac{\sqrt{2} \sqrt[3]{7}}{6} - \frac{\sqrt{2}}{6}\right) ( − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 3 7 + 12 6 ⋅ 7 3 2 ) ) ( − 6 2 + 12 2 3 7 + 12 2 ⋅ 7 3 2 + i ( − 12 6 ⋅ 7 3 2 + 12 6 3 7 ) ) ( − 24 2 ⋅ 4 ⋅ 7 3 2 − 6 2 3 7 − 6 2 )
− 2 3 - \frac{\sqrt{2}}{3} − 3 2
x1 = 0.42099215515006 + 0.356477207629844*i
x2 = 0.42099215515006 - 0.356477207629844*i