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(x-2)(x+5)^2/-x-2>0 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
               2        
(x - 2)*(x + 5)         
---------------- - 2 > 0
       -x               
$$-2 + \frac{\left(x - 2\right) \left(x + 5\right)^{2}}{\left(-1\right) x} > 0$$
-2 + ((x - 2)*(x + 5)^2)/((-x)) > 0
Solución detallada
Se da la desigualdad:
$$-2 + \frac{\left(x - 2\right) \left(x + 5\right)^{2}}{\left(-1\right) x} > 0$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$-2 + \frac{\left(x - 2\right) \left(x + 5\right)^{2}}{\left(-1\right) x} = 0$$
Resolvemos:
$$x_{1} = - \frac{8}{3} + \left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}} + \frac{43}{9 \left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}}$$
$$x_{2} = - \frac{8}{3} + \frac{43}{9 \left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
$$x_{3} = - \frac{8}{3} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
Descartamos las soluciones complejas:
$$x_{1} = - \frac{8}{3} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
Las raíces dadas
$$x_{1} = - \frac{8}{3} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} < x_{1}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{1}{10} + \left(- \frac{8}{3} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}\right)$$
=
$$- \frac{83}{30} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
lo sustituimos en la expresión
$$-2 + \frac{\left(x - 2\right) \left(x + 5\right)^{2}}{\left(-1\right) x} > 0$$
$$-2 + \frac{\left(-2 + \left(- \frac{83}{30} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}\right)\right) \left(\left(- \frac{83}{30} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}\right) + 5\right)^{2}}{\left(-1\right) \left(- \frac{83}{30} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}\right)} > 0$$
                                                             2                                                                
     /          _________________                           \  /             _________________                           \    
     |         /         _______                            |  |            /         _______                            |    
     |67      /  415   \/ 10302                43           |  |  143      /  415   \/ 10302                43           |    
     |-- + 3 /   --- + ---------  + ------------------------| *|- --- + 3 /   --- + ---------  + ------------------------|    
     |30   \/     27       9               _________________|  |   30   \/     27       9               _________________|    
     |                                    /         _______ |  |                                       /         _______ |    
     |                                   /  415   \/ 10302  |  |                                      /  415   \/ 10302  |    
     |                              9*3 /   --- + --------- |  |                                 9*3 /   --- + --------- |    
     \                                \/     27       9     /  \                                   \/     27       9     /    
-2 + --------------------------------------------------------------------------------------------------------------------- > 0
                                               _________________                                                              
                                              /         _______                                                               
                                     83      /  415   \/ 10302                43                                              
                                     -- - 3 /   --- + ---------  - ------------------------                                   
                                     30   \/     27       9               _________________                                   
                                                                         /         _______                                    
                                                                        /  415   \/ 10302                                     
                                                                   9*3 /   --- + ---------                                    
                                                                     \/     27       9                                        
    

significa que la solución de la desigualdad será con:
$$x < - \frac{8}{3} + \frac{43}{9 \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}} + \sqrt[3]{\frac{\sqrt{10302}}{9} + \frac{415}{27}}$$
 _____          
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       x1
Solución de la desigualdad en el gráfico
Respuesta rápida [src]
   /                  / 3      2              \\
And\0 < x, x < CRootOf\x  + 8*x  + 7*x - 50, 0//
$$0 < x \wedge x < \operatorname{CRootOf} {\left(x^{3} + 8 x^{2} + 7 x - 50, 0\right)}$$
(0 < x)∧(x < CRootOf(x^3 + 8*x^2 + 7*x - 50, 0))
Respuesta rápida 2 [src]
           / 3      2              \ 
(0, CRootOf\x  + 8*x  + 7*x - 50, 0/)
$$x\ in\ \left(0, \operatorname{CRootOf} {\left(x^{3} + 8 x^{2} + 7 x - 50, 0\right)}\right)$$
x in Interval.open(0, CRootOf(x^3 + 8*x^2 + 7*x - 50, 0))