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x^3-7x^2-9*x-13=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
 3      2               
x  - 7*x  - 9*x - 13 = 0
$$\left(- 9 x + \left(x^{3} - 7 x^{2}\right)\right) - 13 = 0$$
Teorema de Cardano-Vieta
es ecuación cúbica reducida
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = -7$$
$$q = \frac{c}{a}$$
$$q = -9$$
$$v = \frac{d}{a}$$
$$v = -13$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 7$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = -9$$
$$x_{1} x_{2} x_{3} = -13$$
Gráfica
Respuesta rápida [src]
                                          __________________     /             __________________                            \
                                         /           ______      |            /           ______                             |
                                        /  802   2*\/ 5673       |    ___    /  802   2*\/ 5673                              |
                                     3 /   --- + ----------      |  \/ 3 *3 /   --- + ----------                  ___        |
     7               38              \/     27       9           |        \/     27       9                  38*\/ 3         |
x1 = - - ------------------------- - ----------------------- + I*|- ----------------------------- + -------------------------|
     3          __________________              2                |                2                        __________________|
               /           ______                                |                                        /           ______ |
              /  802   2*\/ 5673                                 |                                       /  802   2*\/ 5673  |
         9*3 /   --- + ----------                                |                                  9*3 /   --- + ---------- |
           \/     27       9                                     \                                    \/     27       9      /
$$x_{1} = - \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} + \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}\right)$$
                                          __________________     /           __________________                            \
                                         /           ______      |          /           ______                             |
                                        /  802   2*\/ 5673       |  ___    /  802   2*\/ 5673                              |
                                     3 /   --- + ----------      |\/ 3 *3 /   --- + ----------                  ___        |
     7               38              \/     27       9           |      \/     27       9                  38*\/ 3         |
x2 = - - ------------------------- - ----------------------- + I*|----------------------------- - -------------------------|
     3          __________________              2                |              2                        __________________|
               /           ______                                |                                      /           ______ |
              /  802   2*\/ 5673                                 |                                     /  802   2*\/ 5673  |
         9*3 /   --- + ----------                                |                                9*3 /   --- + ---------- |
           \/     27       9                                     \                                  \/     27       9      /
$$x_{2} = - \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2}\right)$$
              __________________                            
             /           ______                             
     7      /  802   2*\/ 5673                 76           
x3 = - + 3 /   --- + ----------  + -------------------------
     3   \/     27       9                __________________
                                         /           ______ 
                                        /  802   2*\/ 5673  
                                   9*3 /   --- + ---------- 
                                     \/     27       9      
$$x_{3} = \frac{7}{3} + \frac{76}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}$$
x3 = 7/3 + 76/(9*(2*sqrt(5673)/9 + 802/27)^(1/3)) + (2*sqrt(5673)/9 + 802/27)^(1/3)
Suma y producto de raíces [src]
suma
                                     __________________     /             __________________                            \                                        __________________     /           __________________                            \                                                          
                                    /           ______      |            /           ______                             |                                       /           ______      |          /           ______                             |                                                          
                                   /  802   2*\/ 5673       |    ___    /  802   2*\/ 5673                              |                                      /  802   2*\/ 5673       |  ___    /  802   2*\/ 5673                              |            __________________                            
                                3 /   --- + ----------      |  \/ 3 *3 /   --- + ----------                  ___        |                                   3 /   --- + ----------      |\/ 3 *3 /   --- + ----------                  ___        |           /           ______                             
7               38              \/     27       9           |        \/     27       9                  38*\/ 3         |   7               38              \/     27       9           |      \/     27       9                  38*\/ 3         |   7      /  802   2*\/ 5673                 76           
- - ------------------------- - ----------------------- + I*|- ----------------------------- + -------------------------| + - - ------------------------- - ----------------------- + I*|----------------------------- - -------------------------| + - + 3 /   --- + ----------  + -------------------------
3          __________________              2                |                2                        __________________|   3          __________________              2                |              2                        __________________|   3   \/     27       9                __________________
          /           ______                                |                                        /           ______ |             /           ______                                |                                      /           ______ |                                       /           ______ 
         /  802   2*\/ 5673                                 |                                       /  802   2*\/ 5673  |            /  802   2*\/ 5673                                 |                                     /  802   2*\/ 5673  |                                      /  802   2*\/ 5673  
    9*3 /   --- + ----------                                |                                  9*3 /   --- + ---------- |       9*3 /   --- + ----------                                |                                9*3 /   --- + ---------- |                                 9*3 /   --- + ---------- 
      \/     27       9                                     \                                    \/     27       9      /         \/     27       9                                     \                                  \/     27       9      /                                   \/     27       9      
$$\left(\frac{7}{3} + \frac{76}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}\right) + \left(\left(- \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} + \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}\right)\right) + \left(- \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2}\right)\right)\right)$$
=
      /           __________________                            \     /             __________________                            \
      |          /           ______                             |     |            /           ______                             |
      |  ___    /  802   2*\/ 5673                              |     |    ___    /  802   2*\/ 5673                              |
      |\/ 3 *3 /   --- + ----------                  ___        |     |  \/ 3 *3 /   --- + ----------                  ___        |
      |      \/     27       9                  38*\/ 3         |     |        \/     27       9                  38*\/ 3         |
7 + I*|----------------------------- - -------------------------| + I*|- ----------------------------- + -------------------------|
      |              2                        __________________|     |                2                        __________________|
      |                                      /           ______ |     |                                        /           ______ |
      |                                     /  802   2*\/ 5673  |     |                                       /  802   2*\/ 5673  |
      |                                9*3 /   --- + ---------- |     |                                  9*3 /   --- + ---------- |
      \                                  \/     27       9      /     \                                    \/     27       9      /
$$7 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} + \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}\right) + i \left(- \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2}\right)$$
producto
/                                     __________________     /             __________________                            \\ /                                     __________________     /           __________________                            \\                                                          
|                                    /           ______      |            /           ______                             || |                                    /           ______      |          /           ______                             ||                                                          
|                                   /  802   2*\/ 5673       |    ___    /  802   2*\/ 5673                              || |                                   /  802   2*\/ 5673       |  ___    /  802   2*\/ 5673                              || /         __________________                            \
|                                3 /   --- + ----------      |  \/ 3 *3 /   --- + ----------                  ___        || |                                3 /   --- + ----------      |\/ 3 *3 /   --- + ----------                  ___        || |        /           ______                             |
|7               38              \/     27       9           |        \/     27       9                  38*\/ 3         || |7               38              \/     27       9           |      \/     27       9                  38*\/ 3         || |7      /  802   2*\/ 5673                 76           |
|- - ------------------------- - ----------------------- + I*|- ----------------------------- + -------------------------||*|- - ------------------------- - ----------------------- + I*|----------------------------- - -------------------------||*|- + 3 /   --- + ----------  + -------------------------|
|3          __________________              2                |                2                        __________________|| |3          __________________              2                |              2                        __________________|| |3   \/     27       9                __________________|
|          /           ______                                |                                        /           ______ || |          /           ______                                |                                      /           ______ || |                                    /           ______ |
|         /  802   2*\/ 5673                                 |                                       /  802   2*\/ 5673  || |         /  802   2*\/ 5673                                 |                                     /  802   2*\/ 5673  || |                                   /  802   2*\/ 5673  |
|    9*3 /   --- + ----------                                |                                  9*3 /   --- + ---------- || |    9*3 /   --- + ----------                                |                                9*3 /   --- + ---------- || |                              9*3 /   --- + ---------- |
\      \/     27       9                                     \                                    \/     27       9      // \      \/     27       9                                     \                                  \/     27       9      // \                                \/     27       9      /
$$\left(- \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2}\right)\right) \left(- \frac{\sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} - \frac{38}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \frac{7}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}{2} + \frac{38 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}}\right)\right) \left(\frac{7}{3} + \frac{76}{9 \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}} + \sqrt[3]{\frac{2 \sqrt{5673}}{9} + \frac{802}{27}}\right)$$
=
13
$$13$$
13
Respuesta numérica [src]
x1 = 8.27709117277217
x2 = -0.638545586386086 + 1.07835968354008*i
x3 = -0.638545586386086 - 1.07835968354008*i
x3 = -0.638545586386086 - 1.07835968354008*i