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x^3-3x+1=0

x^3-3x+1=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
 3              
x  - 3*x + 1 = 0
$$\left(x^{3} - 3 x\right) + 1 = 0$$
Teorema de Cardano-Vieta
es ecuación cúbica reducida
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = 0$$
$$q = \frac{c}{a}$$
$$q = -3$$
$$v = \frac{d}{a}$$
$$v = 1$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = 0$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = -3$$
$$x_{1} x_{2} x_{3} = 1$$
Gráfica
Respuesta rápida [src]
        /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\
     cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|
        \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /
x1 = ------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| + -------------| - -------------
        2          |                     _________________|     |   2          |                     _________________|         2      |         2      
                   |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                
                   ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                
                   ||- - - -------|*3 /   -- + ---------- |     |              ||- - - -------|*3 /   -- + ---------- |                |                
                   \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                
$$x_{1} = - \frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} + i \left(- 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2}\right)$$
        /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\
     cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|
        \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /
x2 = ------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| - -------------| + -------------
        2          |                     _________________|     |   2          |                     _________________|         2      |         2      
                   |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                
                   ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                
                   ||- - + -------|*3 /   -- + ---------- |     |              ||- - + -------|*3 /   -- + ---------- |                |                
                   \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                
$$x_{2} = \frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + i \left(- \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)}\right)$$
                                     _________________
                                    /             ___ 
                                   /  27   27*I*\/ 3  
                                3 /   -- + ---------- 
                 3              \/    2        2      
x3 = - ---------------------- - ----------------------
            _________________             3           
           /             ___                          
          /  27   27*I*\/ 3                           
       3 /   -- + ----------                          
       \/    2        2                               
$$x_{3} = - \frac{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}{3} - \frac{3}{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}$$
x3 = -(27/2 + 27*sqrt(3)*i/2)^(1/3)/3 - 3/(27/2 + 27*sqrt(3)*i/2)^(1/3)
Suma y producto de raíces [src]
suma
                                                                                                                                                                                                                                                                                                                                            _________________
                                                                                                                                                                                                                                                                                                                                           /             ___ 
   /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\      /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\                                 /  27   27*I*\/ 3  
cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|   cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|                              3 /   -- + ---------- 
   \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /      \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /               3              \/    2        2      
------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| + -------------| - ------------- + ------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| - -------------| + ------------- + - ---------------------- - ----------------------
   2          |                     _________________|     |   2          |                     _________________|         2      |         2            2          |                     _________________|     |   2          |                     _________________|         2      |         2                _________________             3           
              |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                                 |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                         /             ___                          
              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                                 ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                        /  27   27*I*\/ 3                           
              ||- - - -------|*3 /   -- + ---------- |     |              ||- - - -------|*3 /   -- + ---------- |                |                                 ||- - + -------|*3 /   -- + ---------- |     |              ||- - + -------|*3 /   -- + ---------- |                |                     3 /   -- + ----------                          
              \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                                 \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                     \/    2        2                               
$$\left(\left(\frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + i \left(- \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)}\right)\right) + \left(- \frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} + i \left(- 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2}\right)\right)\right) + \left(- \frac{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}{3} - \frac{3}{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)$$
=
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                                                                                                                             /             ___                                                                                                                                                                     
                                                                                                                            /  27   27*I*\/ 3       /   /pi\                                                    ___    /pi\\     /   /pi\                                                    ___    /pi\\          
                                                                                                                         3 /   -- + ----------      |sin|--|                                                  \/ 3 *cos|--||     |sin|--|                                                  \/ 3 *cos|--||          
            3                  /                  1                   \       /                  1                   \   \/    2        2           |   \9 /       /                  1                   \            \9 /|     |   \9 /       /                  1                   \            \9 /|      /pi\
- ---------------------- - 3*re|--------------------------------------| - 3*re|--------------------------------------| - ---------------------- + I*|------- - 3*im|--------------------------------------| - -------------| + I*|------- - 3*im|--------------------------------------| + -------------| + cos|--|
       _________________       |                     _________________|       |                     _________________|             3                |   2          |                     _________________|         2      |     |   2          |                     _________________|         2      |      \9 /
      /             ___        |/          ___\     /             ___ |       |/          ___\     /             ___ |                              |              |/          ___\     /             ___ |                |     |              |/          ___\     /             ___ |                |          
     /  27   27*I*\/ 3         ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |       ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                              |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |          
  3 /   -- + ----------        ||- - + -------|*3 /   -- + ---------- |       ||- - - -------|*3 /   -- + ---------- |                              |              ||- - + -------|*3 /   -- + ---------- |                |     |              ||- - - -------|*3 /   -- + ---------- |                |          
  \/    2        2             \\  2      2   / \/    2        2      /       \\  2      2   / \/    2        2      /                              \              \\  2      2   / \/    2        2      /                /     \              \\  2      2   / \/    2        2      /                /          
$$- 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \cos{\left(\frac{\pi}{9} \right)} - \frac{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}{3} + i \left(- \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)}\right) + i \left(- 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2}\right) - \frac{3}{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}$$
producto
                                                                                                                                                                                                                                                                                                            /                                _________________\
                                                                                                                                                                                                                                                                                                            |                               /             ___ |
/   /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\\ /   /pi\                                                    /   /pi\                                                    ___    /pi\\     ___    /pi\\ |                              /  27   27*I*\/ 3  |
|cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|| |cos|--|                                                    |sin|--|                                                  \/ 3 *cos|--||   \/ 3 *sin|--|| |                           3 /   -- + ---------- |
|   \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /| |   \9 /       /                  1                   \     |   \9 /       /                  1                   \            \9 /|            \9 /| |            3              \/    2        2      |
|------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| + -------------| - -------------|*|------- - 3*re|--------------------------------------| + I*|------- - 3*im|--------------------------------------| - -------------| + -------------|*|- ---------------------- - ----------------------|
|   2          |                     _________________|     |   2          |                     _________________|         2      |         2      | |   2          |                     _________________|     |   2          |                     _________________|         2      |         2      | |       _________________             3           |
|              |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                | |              |/          ___\     /             ___ |     |              |/          ___\     /             ___ |                |                | |      /             ___                          |
|              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                | |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |     |              ||  1   I*\/ 3 |    /  27   27*I*\/ 3  |                |                | |     /  27   27*I*\/ 3                           |
|              ||- - - -------|*3 /   -- + ---------- |     |              ||- - - -------|*3 /   -- + ---------- |                |                | |              ||- - + -------|*3 /   -- + ---------- |     |              ||- - + -------|*3 /   -- + ---------- |                |                | |  3 /   -- + ----------                          |
\              \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                / \              \\  2      2   / \/    2        2      /     \              \\  2      2   / \/    2        2      /                /                / \  \/    2        2                               /
$$\left(- \frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} + i \left(- 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2}\right)\right) \left(\frac{\sqrt{3} \sin{\left(\frac{\pi}{9} \right)}}{2} + \frac{\cos{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{re}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)} + i \left(- \frac{\sqrt{3} \cos{\left(\frac{\pi}{9} \right)}}{2} + \frac{\sin{\left(\frac{\pi}{9} \right)}}{2} - 3 \operatorname{im}{\left(\frac{1}{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)}\right)\right) \left(- \frac{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}{3} - \frac{3}{\sqrt[3]{\frac{27}{2} + \frac{27 \sqrt{3} i}{2}}}\right)$$
=
  /      /     5*pi*I\  -5*pi*I\        
  |      |     ------|  -------|        
  |      |       9   |     18  |    /pi\
2*\1 - I*\1 - e      /*e       /*cos|--|
                                    \9 /
$$2 \left(1 - i \left(1 - e^{\frac{5 i \pi}{9}}\right) e^{- \frac{5 i \pi}{18}}\right) \cos{\left(\frac{\pi}{9} \right)}$$
2*(1 - i*(1 - exp(5*pi*i/9))*exp(-5*pi*i/18))*cos(pi/9)
Respuesta numérica [src]
x1 = -1.87938524157182
x2 = 0.347296355333861
x3 = 1.53208888623796
x3 = 1.53208888623796
Gráfico
x^3-3x+1=0 la ecuación