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2*x^3-3*x^2-5=0

2*x^3-3*x^2-5=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
   3      2        
2*x  - 3*x  - 5 = 0
$$\left(2 x^{3} - 3 x^{2}\right) - 5 = 0$$
Teorema de Cardano-Vieta
reescribamos la ecuación
$$\left(2 x^{3} - 3 x^{2}\right) - 5 = 0$$
de
$$a x^{3} + b x^{2} + c x + d = 0$$
como ecuación cúbica reducida
$$x^{3} + \frac{b x^{2}}{a} + \frac{c x}{a} + \frac{d}{a} = 0$$
$$x^{3} - \frac{3 x^{2}}{2} - \frac{5}{2} = 0$$
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = - \frac{3}{2}$$
$$q = \frac{c}{a}$$
$$q = 0$$
$$v = \frac{d}{a}$$
$$v = - \frac{5}{2}$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = \frac{3}{2}$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = 0$$
$$x_{1} x_{2} x_{3} = - \frac{5}{2}$$
Gráfica
Suma y producto de raíces [src]
suma
         _____________                            /             _____________                       \            _____________                            /           _____________                       \                                                
        /        ____                             |            /        ____                        |           /        ____                             |          /        ____                        |                                                
       /  11   \/ 30                              |    ___    /  11   \/ 30                         |          /  11   \/ 30                              |  ___    /  11   \/ 30                         |            _____________                       
    3 /   -- + ------                             |  \/ 3 *3 /   -- + ------             ___        |       3 /   -- + ------                             |\/ 3 *3 /   -- + ------             ___        |           /        ____                        
1   \/    8      4                1               |        \/    8      4              \/ 3         |   1   \/    8      4                1               |      \/    8      4              \/ 3         |   1      /  11   \/ 30              1          
- - ------------------ - -------------------- + I*|- ------------------------ + --------------------| + - - ------------------ - -------------------- + I*|------------------------ - --------------------| + - + 3 /   -- + ------  + --------------------
2           2                   _____________     |             2                      _____________|   2           2                   _____________     |           2                      _____________|   2   \/    8      4              _____________
                               /        ____      |                                   /        ____ |                                  /        ____      |                                 /        ____ |                                  /        ____ 
                              /  11   \/ 30       |                                  /  11   \/ 30  |                                 /  11   \/ 30       |                                /  11   \/ 30  |                                 /  11   \/ 30  
                         8*3 /   -- + ------      |                             8*3 /   -- + ------ |                            8*3 /   -- + ------      |                           8*3 /   -- + ------ |                            4*3 /   -- + ------ 
                           \/    8      4         \                               \/    8      4    /                              \/    8      4         \                             \/    8      4    /                              \/    8      4    
$$\left(\frac{1}{4 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}\right) + \left(\left(- \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} + \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}\right)\right) + \left(- \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2}\right)\right)\right)$$
=
      /           _____________                       \     /             _____________                       \
      |          /        ____                        |     |            /        ____                        |
      |  ___    /  11   \/ 30                         |     |    ___    /  11   \/ 30                         |
      |\/ 3 *3 /   -- + ------             ___        |     |  \/ 3 *3 /   -- + ------             ___        |
3     |      \/    8      4              \/ 3         |     |        \/    8      4              \/ 3         |
- + I*|------------------------ - --------------------| + I*|- ------------------------ + --------------------|
2     |           2                      _____________|     |             2                      _____________|
      |                                 /        ____ |     |                                   /        ____ |
      |                                /  11   \/ 30  |     |                                  /  11   \/ 30  |
      |                           8*3 /   -- + ------ |     |                             8*3 /   -- + ------ |
      \                             \/    8      4    /     \                               \/    8      4    /
$$\frac{3}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} + \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}\right) + i \left(- \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2}\right)$$
producto
/         _____________                            /             _____________                       \\ /         _____________                            /           _____________                       \\                                                
|        /        ____                             |            /        ____                        || |        /        ____                             |          /        ____                        ||                                                
|       /  11   \/ 30                              |    ___    /  11   \/ 30                         || |       /  11   \/ 30                              |  ___    /  11   \/ 30                         || /         _____________                       \
|    3 /   -- + ------                             |  \/ 3 *3 /   -- + ------             ___        || |    3 /   -- + ------                             |\/ 3 *3 /   -- + ------             ___        || |        /        ____                        |
|1   \/    8      4                1               |        \/    8      4              \/ 3         || |1   \/    8      4                1               |      \/    8      4              \/ 3         || |1      /  11   \/ 30              1          |
|- - ------------------ - -------------------- + I*|- ------------------------ + --------------------||*|- - ------------------ - -------------------- + I*|------------------------ - --------------------||*|- + 3 /   -- + ------  + --------------------|
|2           2                   _____________     |             2                      _____________|| |2           2                   _____________     |           2                      _____________|| |2   \/    8      4              _____________|
|                               /        ____      |                                   /        ____ || |                               /        ____      |                                 /        ____ || |                               /        ____ |
|                              /  11   \/ 30       |                                  /  11   \/ 30  || |                              /  11   \/ 30       |                                /  11   \/ 30  || |                              /  11   \/ 30  |
|                         8*3 /   -- + ------      |                             8*3 /   -- + ------ || |                         8*3 /   -- + ------      |                           8*3 /   -- + ------ || |                         4*3 /   -- + ------ |
\                           \/    8      4         \                               \/    8      4    // \                           \/    8      4         \                             \/    8      4    // \                           \/    8      4    /
$$\left(- \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2}\right)\right) \left(- \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} + \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}\right)\right) \left(\frac{1}{4 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}\right)$$
=
5/2
$$\frac{5}{2}$$
5/2
Respuesta rápida [src]
              _____________                            /             _____________                       \
             /        ____                             |            /        ____                        |
            /  11   \/ 30                              |    ___    /  11   \/ 30                         |
         3 /   -- + ------                             |  \/ 3 *3 /   -- + ------             ___        |
     1   \/    8      4                1               |        \/    8      4              \/ 3         |
x1 = - - ------------------ - -------------------- + I*|- ------------------------ + --------------------|
     2           2                   _____________     |             2                      _____________|
                                    /        ____      |                                   /        ____ |
                                   /  11   \/ 30       |                                  /  11   \/ 30  |
                              8*3 /   -- + ------      |                             8*3 /   -- + ------ |
                                \/    8      4         \                               \/    8      4    /
$$x_{1} = - \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} + \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}\right)$$
              _____________                            /           _____________                       \
             /        ____                             |          /        ____                        |
            /  11   \/ 30                              |  ___    /  11   \/ 30                         |
         3 /   -- + ------                             |\/ 3 *3 /   -- + ------             ___        |
     1   \/    8      4                1               |      \/    8      4              \/ 3         |
x2 = - - ------------------ - -------------------- + I*|------------------------ - --------------------|
     2           2                   _____________     |           2                      _____________|
                                    /        ____      |                                 /        ____ |
                                   /  11   \/ 30       |                                /  11   \/ 30  |
                              8*3 /   -- + ------      |                           8*3 /   -- + ------ |
                                \/    8      4         \                             \/    8      4    /
$$x_{2} = - \frac{\sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2} - \frac{1}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + i \left(- \frac{\sqrt{3}}{8 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}}{2}\right)$$
              _____________                       
             /        ____                        
     1      /  11   \/ 30              1          
x3 = - + 3 /   -- + ------  + --------------------
     2   \/    8      4              _____________
                                    /        ____ 
                                   /  11   \/ 30  
                              4*3 /   -- + ------ 
                                \/    8      4    
$$x_{3} = \frac{1}{4 \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}} + \frac{1}{2} + \sqrt[3]{\frac{\sqrt{30}}{4} + \frac{11}{8}}$$
x3 = 1/(4*(sqrt(30)/4 + 11/8)^(1/3)) + 1/2 + (sqrt(30)/4 + 11/8)^(1/3)
Respuesta numérica [src]
x1 = -0.289308444254379 - 1.05783905227298*i
x2 = 2.07861688850876
x3 = -0.289308444254379 + 1.05783905227298*i
x3 = -0.289308444254379 + 1.05783905227298*i
Gráfico
2*x^3-3*x^2-5=0 la ecuación