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(((x^2)+5*x+7)^2)-(x+2)*(x-3)<1 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
              2                      
/ 2          \                       
\x  + 5*x + 7/  - (x + 2)*(x - 3) < 1
$$- \left(x - 3\right) \left(x + 2\right) + \left(\left(x^{2} + 5 x\right) + 7\right)^{2} < 1$$
-(x - 3)*(x + 2) + (x^2 + 5*x + 7)^2 < 1
Solución detallada
Se da la desigualdad:
$$- \left(x - 3\right) \left(x + 2\right) + \left(\left(x^{2} + 5 x\right) + 7\right)^{2} < 1$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$- \left(x - 3\right) \left(x + 2\right) + \left(\left(x^{2} + 5 x\right) + 7\right)^{2} = 1$$
Resolvemos:
$$x_{1} = -2$$
$$x_{2} = - \frac{8}{3} + \frac{2}{3 \left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}} - \frac{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3}$$
$$x_{3} = - \frac{8}{3} - \frac{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
$$x_{4} = - \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
Descartamos las soluciones complejas:
$$x_{1} = -2$$
$$x_{2} = - \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
Las raíces dadas
$$x_{2} = - \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
$$x_{1} = -2$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} < x_{2}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{2} - \frac{1}{10}$$
=
$$\left(- \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}\right) + - \frac{1}{10}$$
=
$$- \frac{83}{30} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
lo sustituimos en la expresión
$$- \left(x - 3\right) \left(x + 2\right) + \left(\left(x^{2} + 5 x\right) + 7\right)^{2} < 1$$
$$- \left(\left(- \frac{83}{30} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}\right) - 3\right) \left(\left(- \frac{83}{30} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}\right) + 2\right) + \left(\left(5 \left(- \frac{83}{30} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}\right) + \left(- \frac{83}{30} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}\right)^{2}\right) + 7\right)^{2} < 1$$
                                                                                                                          2                                                                                                                             
/                                                                 2                                                      \                                                                                                                              
|       /            _________________                           \           _________________                           |    /             _________________                           \ /            _________________                           \    
|       |           /           _____                            |          /           _____                            |    |            /           _____                            | |           /           _____                            |    
|       |          /  169   9*\/ 353                             |         /  169   9*\/ 353                             |    |           /  169   9*\/ 353                             | |          /  169   9*\/ 353                             |    
|       |       3 /   --- + ---------                            |    5*3 /   --- + ---------                            |    |        3 /   --- + ---------                            | |       3 /   --- + ---------                            |    
|  41   |  83   \/     2        2                   2            |      \/     2        2                   10           |    |  173   \/     2        2                   2            | |  23   \/     2        2                   2            | < 1
|- -- + |- -- - ---------------------- + ------------------------|  - ------------------------ + ------------------------|  - |- --- - ---------------------- + ------------------------|*|- -- - ---------------------- + ------------------------|    
|  6    |  30             3                     _________________|               3                      _________________|    |   30             3                     _________________| |  30             3                     _________________|    
|       |                                      /           _____ |                                     /           _____ |    |                                       /           _____ | |                                      /           _____ |    
|       |                                     /  169   9*\/ 353  |                                    /  169   9*\/ 353  |    |                                      /  169   9*\/ 353  | |                                     /  169   9*\/ 353  |    
|       |                                3*3 /   --- + --------- |                               3*3 /   --- + --------- |    |                                 3*3 /   --- + --------- | |                                3*3 /   --- + --------- |    
\       \                                  \/     2        2     /                                 \/     2        2     /    \                                   \/     2        2     / \                                  \/     2        2     /    

pero
                                                                                                                          2                                                                                                                             
/                                                                 2                                                      \                                                                                                                              
|       /            _________________                           \           _________________                           |    /             _________________                           \ /            _________________                           \    
|       |           /           _____                            |          /           _____                            |    |            /           _____                            | |           /           _____                            |    
|       |          /  169   9*\/ 353                             |         /  169   9*\/ 353                             |    |           /  169   9*\/ 353                             | |          /  169   9*\/ 353                             |    
|       |       3 /   --- + ---------                            |    5*3 /   --- + ---------                            |    |        3 /   --- + ---------                            | |       3 /   --- + ---------                            |    
|  41   |  83   \/     2        2                   2            |      \/     2        2                   10           |    |  173   \/     2        2                   2            | |  23   \/     2        2                   2            | > 1
|- -- + |- -- - ---------------------- + ------------------------|  - ------------------------ + ------------------------|  - |- --- - ---------------------- + ------------------------|*|- -- - ---------------------- + ------------------------|    
|  6    |  30             3                     _________________|               3                      _________________|    |   30             3                     _________________| |  30             3                     _________________|    
|       |                                      /           _____ |                                     /           _____ |    |                                       /           _____ | |                                      /           _____ |    
|       |                                     /  169   9*\/ 353  |                                    /  169   9*\/ 353  |    |                                      /  169   9*\/ 353  | |                                     /  169   9*\/ 353  |    
|       |                                3*3 /   --- + --------- |                               3*3 /   --- + --------- |    |                                 3*3 /   --- + --------- | |                                3*3 /   --- + --------- |    
\       \                                  \/     2        2     /                                 \/     2        2     /    \                                   \/     2        2     / \                                  \/     2        2     /    

Entonces
$$x < - \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x > - \frac{8}{3} - \frac{\sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}}{3} + \frac{2}{3 \sqrt[3]{\frac{169}{2} + \frac{9 \sqrt{353}}{2}}} \wedge x < -2$$
         _____  
        /     \  
-------ο-------ο-------
       x2      x1
Solución de la desigualdad en el gráfico
Respuesta rápida 2 [src]
        / 3      2               \     
(CRootOf\x  + 8*x  + 22*x + 27, 0/, -2)
$$x\ in\ \left(\operatorname{CRootOf} {\left(x^{3} + 8 x^{2} + 22 x + 27, 0\right)}, -2\right)$$
x in Interval.open(CRootOf(x^3 + 8*x^2 + 22*x + 27, 0), -2)
Respuesta rápida [src]
   /               / 3      2               \    \
And\x < -2, CRootOf\x  + 8*x  + 22*x + 27, 0/ < x/
$$x < -2 \wedge \operatorname{CRootOf} {\left(x^{3} + 8 x^{2} + 22 x + 27, 0\right)} < x$$
(x < -2)∧(CRootOf(x^3 + 8*x^2 + 22*x + 27, 0) < x)