Teorema de Cardano-Vieta
reescribamos la ecuación
$$f x = x^{3}$$
de
$$a x^{3} + b x^{2} + c x + d = 0$$
como ecuación cúbica reducida
$$x^{3} + \frac{b x^{2}}{a} + \frac{c x}{a} + \frac{d}{a} = 0$$
$$- f x + x^{3} = 0$$
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = 0$$
$$q = \frac{c}{a}$$
$$q = - f$$
$$v = \frac{d}{a}$$
$$v = 0$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 0$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = - f$$
$$x_{1} x_{2} x_{3} = 0$$
Suma y producto de raíces
[src]
_________________ _________________ _________________ _________________
4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\
- \/ im (f) + re (f) *cos|-------------------| - I*\/ im (f) + re (f) *sin|-------------------| + \/ im (f) + re (f) *cos|-------------------| + I*\/ im (f) + re (f) *sin|-------------------|
\ 2 / \ 2 / \ 2 / \ 2 /
$$\left(- i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} - \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}\right) + \left(i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} + \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}\right)$$
$$0$$
/ _________________ _________________ \ / _________________ _________________ \
| 4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\| |4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\|
0*|- \/ im (f) + re (f) *cos|-------------------| - I*\/ im (f) + re (f) *sin|-------------------||*|\/ im (f) + re (f) *cos|-------------------| + I*\/ im (f) + re (f) *sin|-------------------||
\ \ 2 / \ 2 // \ \ 2 / \ 2 //
$$0 \left(- i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} - \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}\right) \left(i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} + \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}\right)$$
$$0$$
$$x_{1} = 0$$
_________________ _________________
4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\
x2 = - \/ im (f) + re (f) *cos|-------------------| - I*\/ im (f) + re (f) *sin|-------------------|
\ 2 / \ 2 /
$$x_{2} = - i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} - \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}$$
_________________ _________________
4 / 2 2 /atan2(im(f), re(f))\ 4 / 2 2 /atan2(im(f), re(f))\
x3 = \/ im (f) + re (f) *cos|-------------------| + I*\/ im (f) + re (f) *sin|-------------------|
\ 2 / \ 2 /
$$x_{3} = i \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)} + \sqrt[4]{\left(\operatorname{re}{\left(f\right)}\right)^{2} + \left(\operatorname{im}{\left(f\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(\operatorname{im}{\left(f\right)},\operatorname{re}{\left(f\right)} \right)}}{2} \right)}$$
x3 = i*(re(f)^2 + im(f)^2)^(1/4)*sin(atan2(im(f, re(f))/2) + (re(f)^2 + im(f)^2)^(1/4)*cos(atan2(im(f), re(f))/2))