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3*x^3+5*x^2-7*x+5=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
   3      2              
3*x  + 5*x  - 7*x + 5 = 0
$$\left(- 7 x + \left(3 x^{3} + 5 x^{2}\right)\right) + 5 = 0$$
Teorema de Cardano-Vieta
reescribamos la ecuación
$$\left(- 7 x + \left(3 x^{3} + 5 x^{2}\right)\right) + 5 = 0$$
de
$$a x^{3} + b x^{2} + c x + d = 0$$
como ecuación cúbica reducida
$$x^{3} + \frac{b x^{2}}{a} + \frac{c x}{a} + \frac{d}{a} = 0$$
$$x^{3} + \frac{5 x^{2}}{3} - \frac{7 x}{3} + \frac{5}{3} = 0$$
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = \frac{5}{3}$$
$$q = \frac{c}{a}$$
$$q = - \frac{7}{3}$$
$$v = \frac{d}{a}$$
$$v = \frac{5}{3}$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = - \frac{5}{3}$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = - \frac{7}{3}$$
$$x_{1} x_{2} x_{3} = \frac{5}{3}$$
Gráfica
Respuesta rápida [src]
               _________________                                /                                       _________________\
              / 1205     ______                                 |                               ___    / 1205     ______ |
           3 /  ---- + \/ 1057                                  |               ___           \/ 3 *3 /  ---- + \/ 1057  |
       5   \/    27                           44                |          44*\/ 3                  \/    27             |
x1 = - - + --------------------- + ------------------------ + I*|- ------------------------ + ---------------------------|
       9             6                    _________________     |         _________________                6             |
                                         / 1205     ______      |        / 1205     ______                               |
                                   27*3 /  ---- + \/ 1057       |  27*3 /  ---- + \/ 1057                                |
                                      \/    27                  \     \/    27                                           /
$$x_{1} = - \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6}\right)$$
               _________________                                /            _________________                           \
              / 1205     ______                                 |    ___    / 1205     ______                            |
           3 /  ---- + \/ 1057                                  |  \/ 3 *3 /  ---- + \/ 1057                  ___        |
       5   \/    27                           44                |        \/    27                        44*\/ 3         |
x2 = - - + --------------------- + ------------------------ + I*|- --------------------------- + ------------------------|
       9             6                    _________________     |               6                       _________________|
                                         / 1205     ______      |                                      / 1205     ______ |
                                   27*3 /  ---- + \/ 1057       |                                27*3 /  ---- + \/ 1057  |
                                      \/    27                  \                                   \/    27             /
$$x_{2} = - \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}\right)$$
                                          _________________
                                         / 1205     ______ 
                                      3 /  ---- + \/ 1057  
       5              88              \/    27             
x3 = - - - ------------------------ - ---------------------
       9          _________________             3          
                 / 1205     ______                         
           27*3 /  ---- + \/ 1057                          
              \/    27                                     
$$x_{3} = - \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{3} - \frac{88}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} - \frac{5}{9}$$
x3 = -(sqrt(1057) + 1205/27)^(1/3)/3 - 88/(27*(sqrt(1057) + 1205/27)^(1/3)) - 5/9
Suma y producto de raíces [src]
suma
          _________________                                /                                       _________________\             _________________                                /            _________________                           \                                        _________________
         / 1205     ______                                 |                               ___    / 1205     ______ |            / 1205     ______                                 |    ___    / 1205     ______                            |                                       / 1205     ______ 
      3 /  ---- + \/ 1057                                  |               ___           \/ 3 *3 /  ---- + \/ 1057  |         3 /  ---- + \/ 1057                                  |  \/ 3 *3 /  ---- + \/ 1057                  ___        |                                    3 /  ---- + \/ 1057  
  5   \/    27                           44                |          44*\/ 3                  \/    27             |     5   \/    27                           44                |        \/    27                        44*\/ 3         |     5              88              \/    27             
- - + --------------------- + ------------------------ + I*|- ------------------------ + ---------------------------| + - - + --------------------- + ------------------------ + I*|- --------------------------- + ------------------------| + - - - ------------------------ - ---------------------
  9             6                    _________________     |         _________________                6             |     9             6                    _________________     |               6                       _________________|     9          _________________             3          
                                    / 1205     ______      |        / 1205     ______                               |                                       / 1205     ______      |                                      / 1205     ______ |               / 1205     ______                         
                              27*3 /  ---- + \/ 1057       |  27*3 /  ---- + \/ 1057                                |                                 27*3 /  ---- + \/ 1057       |                                27*3 /  ---- + \/ 1057  |         27*3 /  ---- + \/ 1057                          
                                 \/    27                  \     \/    27                                           /                                    \/    27                  \                                   \/    27             /            \/    27                                     
$$\left(- \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{3} - \frac{88}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} - \frac{5}{9}\right) + \left(\left(- \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}\right)\right) + \left(- \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6}\right)\right)\right)$$
=
        /                                       _________________\     /            _________________                           \
        |                               ___    / 1205     ______ |     |    ___    / 1205     ______                            |
        |               ___           \/ 3 *3 /  ---- + \/ 1057  |     |  \/ 3 *3 /  ---- + \/ 1057                  ___        |
  5     |          44*\/ 3                  \/    27             |     |        \/    27                        44*\/ 3         |
- - + I*|- ------------------------ + ---------------------------| + I*|- --------------------------- + ------------------------|
  3     |         _________________                6             |     |               6                       _________________|
        |        / 1205     ______                               |     |                                      / 1205     ______ |
        |  27*3 /  ---- + \/ 1057                                |     |                                27*3 /  ---- + \/ 1057  |
        \     \/    27                                           /     \                                   \/    27             /
$$- \frac{5}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}\right) + i \left(- \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6}\right)$$
producto
/          _________________                                /                                       _________________\\ /          _________________                                /            _________________                           \\ /                                     _________________\
|         / 1205     ______                                 |                               ___    / 1205     ______ || |         / 1205     ______                                 |    ___    / 1205     ______                            || |                                    / 1205     ______ |
|      3 /  ---- + \/ 1057                                  |               ___           \/ 3 *3 /  ---- + \/ 1057  || |      3 /  ---- + \/ 1057                                  |  \/ 3 *3 /  ---- + \/ 1057                  ___        || |                                 3 /  ---- + \/ 1057  |
|  5   \/    27                           44                |          44*\/ 3                  \/    27             || |  5   \/    27                           44                |        \/    27                        44*\/ 3         || |  5              88              \/    27             |
|- - + --------------------- + ------------------------ + I*|- ------------------------ + ---------------------------||*|- - + --------------------- + ------------------------ + I*|- --------------------------- + ------------------------||*|- - - ------------------------ - ---------------------|
|  9             6                    _________________     |         _________________                6             || |  9             6                    _________________     |               6                       _________________|| |  9          _________________             3          |
|                                    / 1205     ______      |        / 1205     ______                               || |                                    / 1205     ______      |                                      / 1205     ______ || |            / 1205     ______                         |
|                              27*3 /  ---- + \/ 1057       |  27*3 /  ---- + \/ 1057                                || |                              27*3 /  ---- + \/ 1057       |                                27*3 /  ---- + \/ 1057  || |      27*3 /  ---- + \/ 1057                          |
\                                 \/    27                  \     \/    27                                           // \                                 \/    27                  \                                   \/    27             // \         \/    27                                     /
$$\left(- \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6}\right)\right) \left(- \frac{5}{9} + \frac{44}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} + \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + i \left(- \frac{\sqrt{3} \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{6} + \frac{44 \sqrt{3}}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}\right)\right) \left(- \frac{\sqrt[3]{\sqrt{1057} + \frac{1205}{27}}}{3} - \frac{88}{27 \sqrt[3]{\sqrt{1057} + \frac{1205}{27}}} - \frac{5}{9}\right)$$
=
-5/3
$$- \frac{5}{3}$$
-5/3
Respuesta numérica [src]
x1 = 0.536749990764242 - 0.565804701556744*i
x2 = -2.74016664819515
x3 = 0.536749990764242 + 0.565804701556744*i
x3 = 0.536749990764242 + 0.565804701556744*i