-x^3+12x^2-6x+8=0 la ecuación
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Solución
Teorema de Cardano-Vieta
reescribamos la ecuación
(−6x+(−x3+12x2))+8=0de
ax3+bx2+cx+d=0como ecuación cúbica reducida
x3+abx2+acx+ad=0x3−12x2+6x−8=0px2+qx+v+x3=0donde
p=abp=−12q=acq=6v=adv=−8Fórmulas de Cardano-Vieta
x1+x2+x3=−px1x2+x1x3+x2x3=qx1x2x3=vx1+x2+x3=12x1x2+x1x3+x2x3=6x1x2x3=−8
Gráfica
_______________ / _______________\
3 / ___ | ___ ___ 3 / ___ |
7 \/ 56 + 14*\/ 2 | 7*\/ 3 \/ 3 *\/ 56 + 14*\/ 2 |
x1 = 4 - ------------------ - ------------------ + I*|------------------ - ------------------------|
_______________ 2 | _______________ 2 |
3 / ___ |3 / ___ |
\/ 56 + 14*\/ 2 \\/ 56 + 14*\/ 2 /
x1=−23142+56−3142+567+4+i(−233142+56+3142+5673)
_______________ / _______________ \
3 / ___ | ___ 3 / ___ ___ |
7 \/ 56 + 14*\/ 2 |\/ 3 *\/ 56 + 14*\/ 2 7*\/ 3 |
x2 = 4 - ------------------ - ------------------ + I*|------------------------ - ------------------|
_______________ 2 | 2 _______________|
3 / ___ | 3 / ___ |
\/ 56 + 14*\/ 2 \ \/ 56 + 14*\/ 2 /
x2=−23142+56−3142+567+4+i(−3142+5673+233142+56)
_______________
3 / ___ 14
x3 = 4 + \/ 56 + 14*\/ 2 + ------------------
_______________
3 / ___
\/ 56 + 14*\/ 2
x3=3142+5614+4+3142+56
x3 = 14/(14*sqrt(2) + 56)^(1/3) + 4 + (14*sqrt(2) + 56)^(1/3)
Suma y producto de raíces
[src]
_______________ / _______________\ _______________ / _______________ \
3 / ___ | ___ ___ 3 / ___ | 3 / ___ | ___ 3 / ___ ___ | _______________
7 \/ 56 + 14*\/ 2 | 7*\/ 3 \/ 3 *\/ 56 + 14*\/ 2 | 7 \/ 56 + 14*\/ 2 |\/ 3 *\/ 56 + 14*\/ 2 7*\/ 3 | 3 / ___ 14
4 - ------------------ - ------------------ + I*|------------------ - ------------------------| + 4 - ------------------ - ------------------ + I*|------------------------ - ------------------| + 4 + \/ 56 + 14*\/ 2 + ------------------
_______________ 2 | _______________ 2 | _______________ 2 | 2 _______________| _______________
3 / ___ |3 / ___ | 3 / ___ | 3 / ___ | 3 / ___
\/ 56 + 14*\/ 2 \\/ 56 + 14*\/ 2 / \/ 56 + 14*\/ 2 \ \/ 56 + 14*\/ 2 / \/ 56 + 14*\/ 2
(3142+5614+4+3142+56)+((−23142+56−3142+567+4+i(−233142+56+3142+5673))+(−23142+56−3142+567+4+i(−3142+5673+233142+56)))
/ _______________ \ / _______________\
| ___ 3 / ___ ___ | | ___ ___ 3 / ___ |
|\/ 3 *\/ 56 + 14*\/ 2 7*\/ 3 | | 7*\/ 3 \/ 3 *\/ 56 + 14*\/ 2 |
12 + I*|------------------------ - ------------------| + I*|------------------ - ------------------------|
| 2 _______________| | _______________ 2 |
| 3 / ___ | |3 / ___ |
\ \/ 56 + 14*\/ 2 / \\/ 56 + 14*\/ 2 /
12+i(−233142+56+3142+5673)+i(−3142+5673+233142+56)
/ _______________ / _______________\\ / _______________ / _______________ \\
| 3 / ___ | ___ ___ 3 / ___ || | 3 / ___ | ___ 3 / ___ ___ || / _______________ \
| 7 \/ 56 + 14*\/ 2 | 7*\/ 3 \/ 3 *\/ 56 + 14*\/ 2 || | 7 \/ 56 + 14*\/ 2 |\/ 3 *\/ 56 + 14*\/ 2 7*\/ 3 || | 3 / ___ 14 |
|4 - ------------------ - ------------------ + I*|------------------ - ------------------------||*|4 - ------------------ - ------------------ + I*|------------------------ - ------------------||*|4 + \/ 56 + 14*\/ 2 + ------------------|
| _______________ 2 | _______________ 2 || | _______________ 2 | 2 _______________|| | _______________|
| 3 / ___ |3 / ___ || | 3 / ___ | 3 / ___ || | 3 / ___ |
\ \/ 56 + 14*\/ 2 \\/ 56 + 14*\/ 2 // \ \/ 56 + 14*\/ 2 \ \/ 56 + 14*\/ 2 // \ \/ 56 + 14*\/ 2 /
(−23142+56−3142+567+4+i(−3142+5673+233142+56))(−23142+56−3142+567+4+i(−233142+56+3142+5673))(3142+5614+4+3142+56)
x1 = 0.229926352383435 - 0.800228670667707*i
x2 = 0.229926352383435 + 0.800228670667707*i