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x^3-5x^2-9x-45=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
 3      2               
x  - 5*x  - 9*x - 45 = 0
$$\left(- 9 x + \left(x^{3} - 5 x^{2}\right)\right) - 45 = 0$$
Teorema de Cardano-Vieta
es ecuación cúbica reducida
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = -5$$
$$q = \frac{c}{a}$$
$$q = -9$$
$$v = \frac{d}{a}$$
$$v = -45$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 5$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = -9$$
$$x_{1} x_{2} x_{3} = -45$$
Respuesta rápida [src]
                                        ________________     /             ________________                          \
                                       /         ______      |            /         ______                           |
                                      /  935   \/ 9057       |    ___    /  935   \/ 9057                            |
                                   3 /   --- + --------      |  \/ 3 *3 /   --- + --------                 ___       |
     5              26             \/     27      3          |        \/     27      3                26*\/ 3        |
x1 = - - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------|
     3          ________________             2               |               2                       ________________|
               /         ______                              |                                      /         ______ |
              /  935   \/ 9057                               |                                     /  935   \/ 9057  |
         9*3 /   --- + --------                              |                                9*3 /   --- + -------- |
           \/     27      3                                  \                                  \/     27      3     /
$$x_{1} = - \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} + \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}\right)$$
                                        ________________     /           ________________                          \
                                       /         ______      |          /         ______                           |
                                      /  935   \/ 9057       |  ___    /  935   \/ 9057                            |
                                   3 /   --- + --------      |\/ 3 *3 /   --- + --------                 ___       |
     5              26             \/     27      3          |      \/     27      3                26*\/ 3        |
x2 = - - ----------------------- - --------------------- + I*|--------------------------- - -----------------------|
     3          ________________             2               |             2                       ________________|
               /         ______                              |                                    /         ______ |
              /  935   \/ 9057                               |                                   /  935   \/ 9057  |
         9*3 /   --- + --------                              |                              9*3 /   --- + -------- |
           \/     27      3                                  \                                \/     27      3     /
$$x_{2} = - \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2}\right)$$
              ________________                          
             /         ______                           
     5      /  935   \/ 9057                52          
x3 = - + 3 /   --- + --------  + -----------------------
     3   \/     27      3               ________________
                                       /         ______ 
                                      /  935   \/ 9057  
                                 9*3 /   --- + -------- 
                                   \/     27      3     
$$x_{3} = \frac{52}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}$$
x3 = 52/(9*(sqrt(9057)/3 + 935/27)^(1/3)) + 5/3 + (sqrt(9057)/3 + 935/27)^(1/3)
Suma y producto de raíces [src]
suma
                                   ________________     /             ________________                          \                                      ________________     /           ________________                          \                                                      
                                  /         ______      |            /         ______                           |                                     /         ______      |          /         ______                           |                                                      
                                 /  935   \/ 9057       |    ___    /  935   \/ 9057                            |                                    /  935   \/ 9057       |  ___    /  935   \/ 9057                            |            ________________                          
                              3 /   --- + --------      |  \/ 3 *3 /   --- + --------                 ___       |                                 3 /   --- + --------      |\/ 3 *3 /   --- + --------                 ___       |           /         ______                           
5              26             \/     27      3          |        \/     27      3                26*\/ 3        |   5              26             \/     27      3          |      \/     27      3                26*\/ 3        |   5      /  935   \/ 9057                52          
- - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------| + - - ----------------------- - --------------------- + I*|--------------------------- - -----------------------| + - + 3 /   --- + --------  + -----------------------
3          ________________             2               |               2                       ________________|   3          ________________             2               |             2                       ________________|   3   \/     27      3               ________________
          /         ______                              |                                      /         ______ |             /         ______                              |                                    /         ______ |                                     /         ______ 
         /  935   \/ 9057                               |                                     /  935   \/ 9057  |            /  935   \/ 9057                               |                                   /  935   \/ 9057  |                                    /  935   \/ 9057  
    9*3 /   --- + --------                              |                                9*3 /   --- + -------- |       9*3 /   --- + --------                              |                              9*3 /   --- + -------- |                               9*3 /   --- + -------- 
      \/     27      3                                  \                                  \/     27      3     /         \/     27      3                                  \                                \/     27      3     /                                 \/     27      3     
$$\left(\frac{52}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}\right) + \left(\left(- \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} + \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}\right)\right) + \left(- \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2}\right)\right)\right)$$
=
      /           ________________                          \     /             ________________                          \
      |          /         ______                           |     |            /         ______                           |
      |  ___    /  935   \/ 9057                            |     |    ___    /  935   \/ 9057                            |
      |\/ 3 *3 /   --- + --------                 ___       |     |  \/ 3 *3 /   --- + --------                 ___       |
      |      \/     27      3                26*\/ 3        |     |        \/     27      3                26*\/ 3        |
5 + I*|--------------------------- - -----------------------| + I*|- --------------------------- + -----------------------|
      |             2                       ________________|     |               2                       ________________|
      |                                    /         ______ |     |                                      /         ______ |
      |                                   /  935   \/ 9057  |     |                                     /  935   \/ 9057  |
      |                              9*3 /   --- + -------- |     |                                9*3 /   --- + -------- |
      \                                \/     27      3     /     \                                  \/     27      3     /
$$5 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} + \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}\right) + i \left(- \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2}\right)$$
producto
/                                   ________________     /             ________________                          \\ /                                   ________________     /           ________________                          \\                                                      
|                                  /         ______      |            /         ______                           || |                                  /         ______      |          /         ______                           ||                                                      
|                                 /  935   \/ 9057       |    ___    /  935   \/ 9057                            || |                                 /  935   \/ 9057       |  ___    /  935   \/ 9057                            || /         ________________                          \
|                              3 /   --- + --------      |  \/ 3 *3 /   --- + --------                 ___       || |                              3 /   --- + --------      |\/ 3 *3 /   --- + --------                 ___       || |        /         ______                           |
|5              26             \/     27      3          |        \/     27      3                26*\/ 3        || |5              26             \/     27      3          |      \/     27      3                26*\/ 3        || |5      /  935   \/ 9057                52          |
|- - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------||*|- - ----------------------- - --------------------- + I*|--------------------------- - -----------------------||*|- + 3 /   --- + --------  + -----------------------|
|3          ________________             2               |               2                       ________________|| |3          ________________             2               |             2                       ________________|| |3   \/     27      3               ________________|
|          /         ______                              |                                      /         ______ || |          /         ______                              |                                    /         ______ || |                                  /         ______ |
|         /  935   \/ 9057                               |                                     /  935   \/ 9057  || |         /  935   \/ 9057                               |                                   /  935   \/ 9057  || |                                 /  935   \/ 9057  |
|    9*3 /   --- + --------                              |                                9*3 /   --- + -------- || |    9*3 /   --- + --------                              |                              9*3 /   --- + -------- || |                            9*3 /   --- + -------- |
\      \/     27      3                                  \                                  \/     27      3     // \      \/     27      3                                  \                                \/     27      3     // \                              \/     27      3     /
$$\left(- \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2}\right)\right) \left(- \frac{\sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} - \frac{26}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}{2} + \frac{26 \sqrt{3}}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}}\right)\right) \left(\frac{52}{9 \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}} + \frac{5}{3} + \sqrt[3]{\frac{\sqrt{9057}}{3} + \frac{935}{27}}\right)$$
=
45
$$45$$
45
Respuesta numérica [src]
x1 = -1.07112748277456 + 2.27006984051383*i
x2 = 7.14225496554912
x3 = -1.07112748277456 - 2.27006984051383*i
x3 = -1.07112748277456 - 2.27006984051383*i