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2x³-15x²+36x-1 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
   3       2               
2*x  - 15*x  + 36*x - 1 = 0
$$\left(36 x + \left(2 x^{3} - 15 x^{2}\right)\right) - 1 = 0$$
Teorema de Cardano-Vieta
reescribamos la ecuación
$$\left(36 x + \left(2 x^{3} - 15 x^{2}\right)\right) - 1 = 0$$
de
$$a x^{3} + b x^{2} + c x + d = 0$$
como ecuación cúbica reducida
$$x^{3} + \frac{b x^{2}}{a} + \frac{c x}{a} + \frac{d}{a} = 0$$
$$x^{3} - \frac{15 x^{2}}{2} + 18 x - \frac{1}{2} = 0$$
$$p x^{2} + q x + v + x^{3} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = - \frac{15}{2}$$
$$q = \frac{c}{a}$$
$$q = 18$$
$$v = \frac{d}{a}$$
$$v = - \frac{1}{2}$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} + x_{3} = - p$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = q$$
$$x_{1} x_{2} x_{3} = v$$
$$x_{1} + x_{2} + x_{3} = \frac{15}{2}$$
$$x_{1} x_{2} + x_{1} x_{3} + x_{2} x_{3} = 18$$
$$x_{1} x_{2} x_{3} = - \frac{1}{2}$$
Gráfica
Suma y producto de raíces [src]
suma
         __________________                                 /                                         __________________\            __________________                                 /             __________________                            \                                        __________________
        /             ____                                  |                                        /             ____ |           /             ____                                  |            /             ____                             |                                       /             ____ 
       /  1431   81*\/ 78                                   |                                ___    /  1431   81*\/ 78  |          /  1431   81*\/ 78                                   |    ___    /  1431   81*\/ 78                              |                                      /  1431   81*\/ 78  
    3 /   ---- + ---------                                  |               ___            \/ 3 *3 /   ---- + --------- |       3 /   ---- + ---------                                  |  \/ 3 *3 /   ---- + ---------                 ___         |                                   3 /   ---- + --------- 
5   \/     8         4                    3                 |           3*\/ 3                   \/     8         4     |   5   \/     8         4                    3                 |        \/     8         4                 3*\/ 3          |   5               3               \/     8         4     
- + ----------------------- + ------------------------- + I*|- ------------------------- + -----------------------------| + - + ----------------------- + ------------------------- + I*|- ----------------------------- + -------------------------| + - - ------------------------- - -----------------------
2              6                     __________________     |         __________________                 6              |   2              6                     __________________     |                6                        __________________|   2          __________________              3           
                                    /             ____      |        /             ____                                 |                                       /             ____      |                                        /             ____ |             /             ____                           
                                   /  1431   81*\/ 78       |       /  1431   81*\/ 78                                  |                                      /  1431   81*\/ 78       |                                       /  1431   81*\/ 78  |            /  1431   81*\/ 78                            
                              8*3 /   ---- + ---------      |  8*3 /   ---- + ---------                                 |                                 8*3 /   ---- + ---------      |                                  8*3 /   ---- + --------- |       4*3 /   ---- + ---------                           
                                \/     8         4          \    \/     8         4                                     /                                   \/     8         4          \                                    \/     8         4     /         \/     8         4                               
$$\left(- \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{3} - \frac{3}{4 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{5}{2}\right) + \left(\left(\frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}\right)\right) + \left(\frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6}\right)\right)\right)$$
=
       /                                         __________________\     /             __________________                            \
       |                                        /             ____ |     |            /             ____                             |
       |                                ___    /  1431   81*\/ 78  |     |    ___    /  1431   81*\/ 78                              |
       |               ___            \/ 3 *3 /   ---- + --------- |     |  \/ 3 *3 /   ---- + ---------                 ___         |
15     |           3*\/ 3                   \/     8         4     |     |        \/     8         4                 3*\/ 3          |
-- + I*|- ------------------------- + -----------------------------| + I*|- ----------------------------- + -------------------------|
2      |         __________________                 6              |     |                6                        __________________|
       |        /             ____                                 |     |                                        /             ____ |
       |       /  1431   81*\/ 78                                  |     |                                       /  1431   81*\/ 78  |
       |  8*3 /   ---- + ---------                                 |     |                                  8*3 /   ---- + --------- |
       \    \/     8         4                                     /     \                                    \/     8         4     /
$$\frac{15}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}\right) + i \left(- \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6}\right)$$
producto
/         __________________                                 /                                         __________________\\ /         __________________                                 /             __________________                            \\ /                                     __________________\
|        /             ____                                  |                                        /             ____ || |        /             ____                                  |            /             ____                             || |                                    /             ____ |
|       /  1431   81*\/ 78                                   |                                ___    /  1431   81*\/ 78  || |       /  1431   81*\/ 78                                   |    ___    /  1431   81*\/ 78                              || |                                   /  1431   81*\/ 78  |
|    3 /   ---- + ---------                                  |               ___            \/ 3 *3 /   ---- + --------- || |    3 /   ---- + ---------                                  |  \/ 3 *3 /   ---- + ---------                 ___         || |                                3 /   ---- + --------- |
|5   \/     8         4                    3                 |           3*\/ 3                   \/     8         4     || |5   \/     8         4                    3                 |        \/     8         4                 3*\/ 3          || |5               3               \/     8         4     |
|- + ----------------------- + ------------------------- + I*|- ------------------------- + -----------------------------||*|- + ----------------------- + ------------------------- + I*|- ----------------------------- + -------------------------||*|- - ------------------------- - -----------------------|
|2              6                     __________________     |         __________________                 6              || |2              6                     __________________     |                6                        __________________|| |2          __________________              3           |
|                                    /             ____      |        /             ____                                 || |                                    /             ____      |                                        /             ____ || |          /             ____                           |
|                                   /  1431   81*\/ 78       |       /  1431   81*\/ 78                                  || |                                   /  1431   81*\/ 78       |                                       /  1431   81*\/ 78  || |         /  1431   81*\/ 78                            |
|                              8*3 /   ---- + ---------      |  8*3 /   ---- + ---------                                 || |                              8*3 /   ---- + ---------      |                                  8*3 /   ---- + --------- || |    4*3 /   ---- + ---------                           |
\                                \/     8         4          \    \/     8         4                                     // \                                \/     8         4          \                                    \/     8         4     // \      \/     8         4                               /
$$\left(\frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6}\right)\right) \left(\frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}\right)\right) \left(- \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{3} - \frac{3}{4 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{5}{2}\right)$$
=
1/2
$$\frac{1}{2}$$
1/2
Respuesta rápida [src]
              __________________                                 /                                         __________________\
             /             ____                                  |                                        /             ____ |
            /  1431   81*\/ 78                                   |                                ___    /  1431   81*\/ 78  |
         3 /   ---- + ---------                                  |               ___            \/ 3 *3 /   ---- + --------- |
     5   \/     8         4                    3                 |           3*\/ 3                   \/     8         4     |
x1 = - + ----------------------- + ------------------------- + I*|- ------------------------- + -----------------------------|
     2              6                     __________________     |         __________________                 6              |
                                         /             ____      |        /             ____                                 |
                                        /  1431   81*\/ 78       |       /  1431   81*\/ 78                                  |
                                   8*3 /   ---- + ---------      |  8*3 /   ---- + ---------                                 |
                                     \/     8         4          \    \/     8         4                                     /
$$x_{1} = \frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6}\right)$$
              __________________                                 /             __________________                            \
             /             ____                                  |            /             ____                             |
            /  1431   81*\/ 78                                   |    ___    /  1431   81*\/ 78                              |
         3 /   ---- + ---------                                  |  \/ 3 *3 /   ---- + ---------                 ___         |
     5   \/     8         4                    3                 |        \/     8         4                 3*\/ 3          |
x2 = - + ----------------------- + ------------------------- + I*|- ----------------------------- + -------------------------|
     2              6                     __________________     |                6                        __________________|
                                         /             ____      |                                        /             ____ |
                                        /  1431   81*\/ 78       |                                       /  1431   81*\/ 78  |
                                   8*3 /   ---- + ---------      |                                  8*3 /   ---- + --------- |
                                     \/     8         4          \                                    \/     8         4     /
$$x_{2} = \frac{3}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{5}{2} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{6} + \frac{3 \sqrt{3}}{8 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}\right)$$
                                          __________________
                                         /             ____ 
                                        /  1431   81*\/ 78  
                                     3 /   ---- + --------- 
     5               3               \/     8         4     
x3 = - - ------------------------- - -----------------------
     2          __________________              3           
               /             ____                           
              /  1431   81*\/ 78                            
         4*3 /   ---- + ---------                           
           \/     8         4                               
$$x_{3} = - \frac{\sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}}{3} - \frac{3}{4 \sqrt[3]{\frac{81 \sqrt{78}}{4} + \frac{1431}{8}}} + \frac{5}{2}$$
x3 = -(81*sqrt(78)/4 + 1431/8)^(1/3)/3 - 3/(4*(81*sqrt(78)/4 + 1431/8)^(1/3)) + 5/2
Respuesta numérica [src]
x1 = 3.73594715920756 + 1.95772728975712*i
x2 = 0.028105681584872
x3 = 3.73594715920756 - 1.95772728975712*i
x3 = 3.73594715920756 - 1.95772728975712*i