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x^3-1.2*x+0.5=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
 3   6*x   1    
x  - --- + - = 0
      5    2    
$$\left(x^{3} - \frac{6 x}{5}\right) + \frac{1}{2} = 0$$
Teorema de Cardano-Vieta
es ecuación cúbica reducida
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = 0$$
$$q = \frac{c}{a}$$
$$q = - \frac{6}{5}$$
$$v = \frac{d}{a}$$
$$v = \frac{1}{2}$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 0$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = - \frac{6}{5}$$
$$x_{1} x_{2} x_{3} = \frac{1}{2}$$
Gráfica
Suma y producto de raíces [src]
suma
      /                   1                   \     /      /                   1                   \                                                      \                                                               /                   1                   \     /      /                   1                   \                                                      \                                                                                                              
  6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\     6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\                                                        
      |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||         |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||                                      __________________
      |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||         |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||                                     /             ____ 
      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|         ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|                                    /  27   27*I*\/ 15  
      ||- - - -------|*3 /   -- + ----------- |     |      ||- - - -------|*3 /   -- + ----------- |   \/ 10 *sin|------------|   \/ 30 *cos|------------||   \/ 30 *sin|------------|   \/ 10 *cos|------------|         ||- - + -------|*3 /   -- + ----------- |     |      ||- - + -------|*3 /   -- + ----------- |   \/ 30 *cos|------------|   \/ 10 *sin|------------||   \/ 10 *cos|------------|   \/ 30 *sin|------------|                                 3 /   -- + ----------- 
      \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /         \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /                 6               \/    4        100     
- --------------------------------------------- + I*|- --------------------------------------------- + ------------------------ + ------------------------| - ------------------------ + ------------------------ + - --------------------------------------------- + I*|- --------------------------------------------- - ------------------------ + ------------------------| + ------------------------ + ------------------------ + - ------------------------- - -----------------------
                        5                           \                        5                                    10                         10           /              10                         10                                      5                           \                        5                                    10                         10           /              10                         10                       __________________              3           
                                                                                                                                                                                                                                                                                                                                                                                                                                                /             ____                           
                                                                                                                                                                                                                                                                                                                                                                                                                                               /  27   27*I*\/ 15                            
                                                                                                                                                                                                                                                                                                                                                                                                                                          5*3 /   -- + -----------                           
                                                                                                                                                                                                                                                                                                                                                                                                                                            \/    4        100                               
$$\left(\left(- \frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + i \left(- \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10}\right)\right) + \left(\frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + i \left(- \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5}\right)\right)\right) + \left(- \frac{\sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}{3} - \frac{6}{5 \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)$$
=
                                  /                   1                   \       /                   1                   \                               /      /                   1                   \                                                      \     /      /                   1                   \                                                      \                           
                              6*re|---------------------------------------|   6*re|---------------------------------------|                               |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\
                                  |                     __________________|       |                     __________________|        __________________     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||
                                  |/          ___\     /             ____ |       |/          ___\     /             ____ |       /             ____      |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||
                                  ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |       ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |      /  27   27*I*\/ 15       |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|
                                  ||- - + -------|*3 /   -- + ----------- |       ||- - - -------|*3 /   -- + ----------- |   3 /   -- + -----------      |      ||- - + -------|*3 /   -- + ----------- |   \/ 30 *cos|------------|   \/ 10 *sin|------------||     |      ||- - - -------|*3 /   -- + ----------- |   \/ 10 *sin|------------|   \/ 30 *cos|------------||   \/ 10 *cos|------------|
              6                   \\  2      2   / \/    4        100     /       \\  2      2   / \/    4        100     /   \/    4        100          |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /
- ------------------------- - --------------------------------------------- - --------------------------------------------- - ----------------------- + I*|- --------------------------------------------- - ------------------------ + ------------------------| + I*|- --------------------------------------------- + ------------------------ + ------------------------| + ------------------------
         __________________                         5                                               5                                    3                \                        5                                    10                         10           /     \                        5                                    10                         10           /              5            
        /             ____                                                                                                                                                                                                                                                                                                                                                                              
       /  27   27*I*\/ 15                                                                                                                                                                                                                                                                                                                                                                               
  5*3 /   -- + -----------                                                                                                                                                                                                                                                                                                                                                                              
    \/    4        100                                                                                                                                                                                                                                                                                                                                                                                  
$$- \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{5} - \frac{\sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}{3} + i \left(- \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5}\right) + i \left(- \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10}\right) - \frac{6}{5 \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}$$
producto
/      /                   1                   \     /      /                   1                   \                                                      \                                                      \ /      /                   1                   \     /      /                   1                   \                                                      \                                                      \                                                        
|  6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\| |  6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\|                                                        
|      |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||| |      |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||| /                                   __________________\
|      |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||| |      |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||| |                                  /             ____ |
|      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|| |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|| |                                 /  27   27*I*\/ 15  |
|      ||- - - -------|*3 /   -- + ----------- |     |      ||- - - -------|*3 /   -- + ----------- |   \/ 10 *sin|------------|   \/ 30 *cos|------------||   \/ 30 *sin|------------|   \/ 10 *cos|------------|| |      ||- - + -------|*3 /   -- + ----------- |     |      ||- - + -------|*3 /   -- + ----------- |   \/ 30 *cos|------------|   \/ 10 *sin|------------||   \/ 10 *cos|------------|   \/ 30 *sin|------------|| |                              3 /   -- + ----------- |
|      \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /| |      \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /| |              6               \/    4        100     |
|- --------------------------------------------- + I*|- --------------------------------------------- + ------------------------ + ------------------------| - ------------------------ + ------------------------|*|- --------------------------------------------- + I*|- --------------------------------------------- - ------------------------ + ------------------------| + ------------------------ + ------------------------|*|- ------------------------- - -----------------------|
\                        5                           \                        5                                    10                         10           /              10                         10           / \                        5                           \                        5                                    10                         10           /              10                         10           / |         __________________              3           |
                                                                                                                                                                                                                                                                                                                                                                                                                                        |        /             ____                           |
                                                                                                                                                                                                                                                                                                                                                                                                                                        |       /  27   27*I*\/ 15                            |
                                                                                                                                                                                                                                                                                                                                                                                                                                        |  5*3 /   -- + -----------                           |
                                                                                                                                                                                                                                                                                                                                                                                                                                        \    \/    4        100                               /
$$\left(- \frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + i \left(- \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10}\right)\right) \left(\frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + i \left(- \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5}\right)\right) \left(- \frac{\sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}{3} - \frac{6}{5 \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)$$
=
       /         /      /  ____\\\                                
       |         |      |\/ 15 |||                                
       |         |2*atan|------||| /               2/3           \
3 ____ |         |      \  25  /|| |/         ____\        3 ____|
\/ 10 *|1 - 2*cos|--------------||*\\25 + I*\/ 15 /    + 4*\/ 10 /
       \         \      3       //                                
------------------------------------------------------------------
                            _______________                       
                         3 /          ____                        
                      25*\/  25 + I*\/ 15                         
$$\frac{\sqrt[3]{10} \left(1 - 2 \cos{\left(\frac{2 \operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}\right) \left(4 \sqrt[3]{10} + \left(25 + \sqrt{15} i\right)^{\frac{2}{3}}\right)}{25 \sqrt[3]{25 + \sqrt{15} i}}$$
10^(1/3)*(1 - 2*cos(2*atan(sqrt(15)/25)/3))*((25 + i*sqrt(15))^(2/3) + 4*10^(1/3))/(25*(25 + i*sqrt(15))^(1/3))
Respuesta rápida [src]
           /                   1                   \     /      /                   1                   \                                                      \                                                      
       6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\
           |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||
           |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||
           ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|
           ||- - - -------|*3 /   -- + ----------- |     |      ||- - - -------|*3 /   -- + ----------- |   \/ 10 *sin|------------|   \/ 30 *cos|------------||   \/ 30 *sin|------------|   \/ 10 *cos|------------|
           \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /
x1 = - --------------------------------------------- + I*|- --------------------------------------------- + ------------------------ + ------------------------| - ------------------------ + ------------------------
                             5                           \                        5                                    10                         10           /              10                         10           
$$x_{1} = - \frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + i \left(- \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10}\right)$$
           /                   1                   \     /      /                   1                   \                                                      \                                                      
       6*re|---------------------------------------|     |  6*im|---------------------------------------|             /    /  ____\\             /    /  ____\\|             /    /  ____\\             /    /  ____\\
           |                     __________________|     |      |                     __________________|             |    |\/ 15 ||             |    |\/ 15 |||             |    |\/ 15 ||             |    |\/ 15 ||
           |/          ___\     /             ____ |     |      |/          ___\     /             ____ |             |atan|------||             |atan|------|||             |atan|------||             |atan|------||
           ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     |      ||  1   I*\/ 3 |    /  27   27*I*\/ 15  |     ____    |    \  25  /|     ____    |    \  25  /||     ____    |    \  25  /|     ____    |    \  25  /|
           ||- - + -------|*3 /   -- + ----------- |     |      ||- - + -------|*3 /   -- + ----------- |   \/ 30 *cos|------------|   \/ 10 *sin|------------||   \/ 10 *cos|------------|   \/ 30 *sin|------------|
           \\  2      2   / \/    4        100     /     |      \\  2      2   / \/    4        100     /             \     3      /             \     3      /|             \     3      /             \     3      /
x2 = - --------------------------------------------- + I*|- --------------------------------------------- - ------------------------ + ------------------------| + ------------------------ + ------------------------
                             5                           \                        5                                    10                         10           /              10                         10           
$$x_{2} = \frac{\sqrt{30} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5} + i \left(- \frac{\sqrt{30} \cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} + \frac{\sqrt{10} \sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{15}}{25} \right)}}{3} \right)}}{10} - \frac{6 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}\right)}}{5}\right)$$
                                        __________________
                                       /             ____ 
                                      /  27   27*I*\/ 15  
                                   3 /   -- + ----------- 
                   6               \/    4        100     
x3 = - ------------------------- - -----------------------
              __________________              3           
             /             ____                           
            /  27   27*I*\/ 15                            
       5*3 /   -- + -----------                           
         \/    4        100                               
$$x_{3} = - \frac{\sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}{3} - \frac{6}{5 \sqrt[3]{\frac{27}{4} + \frac{27 \sqrt{15} i}{100}}}$$
x3 = -(27/4 + 27*sqrt(15)*i/100)^(1/3)/3 - 6/(5*(27/4 + 27*sqrt(15)*i/100)^(1/3))
Respuesta numérica [src]
x1 = 0.575527835434157
x2 = -1.26325137687806
x3 = 0.687723541443907
x3 = 0.687723541443907