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x^3+2*x-126=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
 3                
x  + 2*x - 126 = 0
$$\left(x^{3} + 2 x\right) - 126 = 0$$
Teorema de Cardano-Vieta
es ecuación cúbica reducida
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = 0$$
$$q = \frac{c}{a}$$
$$q = 2$$
$$v = \frac{d}{a}$$
$$v = -126$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 0$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = 2$$
$$x_{1} x_{2} x_{3} = -126$$
Suma y producto de raíces [src]
suma
       _________________                                /             _________________                           \          _________________                                /           _________________                           \                                                    
      /        ________                                 |            /        ________                            |         /        ________                                 |          /        ________                            |                                                    
     /       \/ 321513                                  |    ___    /       \/ 321513                             |        /       \/ 321513                                  |  ___    /       \/ 321513                             |        _________________                           
  3 /   63 + ----------                                 |  \/ 3 *3 /   63 + ----------               ___          |     3 /   63 + ----------                                 |\/ 3 *3 /   63 + ----------               ___          |       /        ________                            
  \/             9                    1                 |        \/             9                  \/ 3           |     \/             9                    1                 |      \/             9                  \/ 3           |      /       \/ 321513                2            
- ---------------------- + ------------------------ + I*|- ---------------------------- - ------------------------| + - ---------------------- + ------------------------ + I*|---------------------------- + ------------------------| + 3 /   63 + ----------  - ------------------------
            2                     _________________     |               2                        _________________|               2                     _________________     |             2                        _________________|   \/             9                _________________
                                 /        ________      |                                       /        ________ |                                    /        ________      |                                     /        ________ |                                  /        ________ 
                                /       \/ 321513       |                                      /       \/ 321513  |                                   /       \/ 321513       |                                    /       \/ 321513  |                                 /       \/ 321513  
                           3*3 /   63 + ----------      |                                 3*3 /   63 + ---------- |                              3*3 /   63 + ----------      |                               3*3 /   63 + ---------- |                            3*3 /   63 + ---------- 
                             \/             9           \                                   \/             9      /                                \/             9           \                                 \/             9      /                              \/             9      
$$\left(- \frac{2}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}\right) + \left(\left(- \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(- \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} - \frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}\right)\right) + \left(- \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(\frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2}\right)\right)\right)$$
=
  /           _________________                           \     /             _________________                           \
  |          /        ________                            |     |            /        ________                            |
  |  ___    /       \/ 321513                             |     |    ___    /       \/ 321513                             |
  |\/ 3 *3 /   63 + ----------               ___          |     |  \/ 3 *3 /   63 + ----------               ___          |
  |      \/             9                  \/ 3           |     |        \/             9                  \/ 3           |
I*|---------------------------- + ------------------------| + I*|- ---------------------------- - ------------------------|
  |             2                        _________________|     |               2                        _________________|
  |                                     /        ________ |     |                                       /        ________ |
  |                                    /       \/ 321513  |     |                                      /       \/ 321513  |
  |                               3*3 /   63 + ---------- |     |                                 3*3 /   63 + ---------- |
  \                                 \/             9      /     \                                   \/             9      /
$$i \left(- \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} - \frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}\right) + i \left(\frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2}\right)$$
producto
/       _________________                                /             _________________                           \\ /       _________________                                /           _________________                           \\                                                    
|      /        ________                                 |            /        ________                            || |      /        ________                                 |          /        ________                            ||                                                    
|     /       \/ 321513                                  |    ___    /       \/ 321513                             || |     /       \/ 321513                                  |  ___    /       \/ 321513                             || /     _________________                           \
|  3 /   63 + ----------                                 |  \/ 3 *3 /   63 + ----------               ___          || |  3 /   63 + ----------                                 |\/ 3 *3 /   63 + ----------               ___          || |    /        ________                            |
|  \/             9                    1                 |        \/             9                  \/ 3           || |  \/             9                    1                 |      \/             9                  \/ 3           || |   /       \/ 321513                2            |
|- ---------------------- + ------------------------ + I*|- ---------------------------- - ------------------------||*|- ---------------------- + ------------------------ + I*|---------------------------- + ------------------------||*|3 /   63 + ----------  - ------------------------|
|            2                     _________________     |               2                        _________________|| |            2                     _________________     |             2                        _________________|| |\/             9                _________________|
|                                 /        ________      |                                       /        ________ || |                                 /        ________      |                                     /        ________ || |                               /        ________ |
|                                /       \/ 321513       |                                      /       \/ 321513  || |                                /       \/ 321513       |                                    /       \/ 321513  || |                              /       \/ 321513  |
|                           3*3 /   63 + ----------      |                                 3*3 /   63 + ---------- || |                           3*3 /   63 + ----------      |                               3*3 /   63 + ---------- || |                         3*3 /   63 + ---------- |
\                             \/             9           \                                   \/             9      // \                             \/             9           \                                 \/             9      // \                           \/             9      /
$$\left(- \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(\frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2}\right)\right) \left(- \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(- \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} - \frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}\right)\right) \left(- \frac{2}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}\right)$$
=
126
$$126$$
126
Respuesta rápida [src]
            _________________                                /             _________________                           \
           /        ________                                 |            /        ________                            |
          /       \/ 321513                                  |    ___    /       \/ 321513                             |
       3 /   63 + ----------                                 |  \/ 3 *3 /   63 + ----------               ___          |
       \/             9                    1                 |        \/             9                  \/ 3           |
x1 = - ---------------------- + ------------------------ + I*|- ---------------------------- - ------------------------|
                 2                     _________________     |               2                        _________________|
                                      /        ________      |                                       /        ________ |
                                     /       \/ 321513       |                                      /       \/ 321513  |
                                3*3 /   63 + ----------      |                                 3*3 /   63 + ---------- |
                                  \/             9           \                                   \/             9      /
$$x_{1} = - \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(- \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} - \frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}\right)$$
            _________________                                /           _________________                           \
           /        ________                                 |          /        ________                            |
          /       \/ 321513                                  |  ___    /       \/ 321513                             |
       3 /   63 + ----------                                 |\/ 3 *3 /   63 + ----------               ___          |
       \/             9                    1                 |      \/             9                  \/ 3           |
x2 = - ---------------------- + ------------------------ + I*|---------------------------- + ------------------------|
                 2                     _________________     |             2                        _________________|
                                      /        ________      |                                     /        ________ |
                                     /       \/ 321513       |                                    /       \/ 321513  |
                                3*3 /   63 + ----------      |                               3*3 /   63 + ---------- |
                                  \/             9           \                                 \/             9      /
$$x_{2} = - \frac{\sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2} + \frac{1}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + i \left(\frac{\sqrt{3}}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \frac{\sqrt{3} \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}}{2}\right)$$
          _________________                           
         /        ________                            
        /       \/ 321513                2            
x3 = 3 /   63 + ----------  - ------------------------
     \/             9                _________________
                                    /        ________ 
                                   /       \/ 321513  
                              3*3 /   63 + ---------- 
                                \/             9      
$$x_{3} = - \frac{2}{3 \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}} + \sqrt[3]{63 + \frac{\sqrt{321513}}{9}}$$
x3 = -2/(3*(63 + sqrt(321513)/9)^(1/3)) + (63 + sqrt(321513)/9)^(1/3)
Respuesta numérica [src]
x1 = -2.44017514353687 + 4.45683342670618*i
x2 = 4.88035028707374
x3 = -2.44017514353687 - 4.45683342670618*i
x3 = -2.44017514353687 - 4.45683342670618*i