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(10x^3+81x^2+8x+8)/(x+8)>=0

(10x^3+81x^2+8x+8)/(x+8)>=0 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
    3       2               
10*x  + 81*x  + 8*x + 8     
----------------------- >= 0
         x + 8              
$$\frac{\left(8 x + \left(10 x^{3} + 81 x^{2}\right)\right) + 8}{x + 8} \geq 0$$
(8*x + 10*x^3 + 81*x^2 + 8)/(x + 8) >= 0
Solución detallada
Se da la desigualdad:
$$\frac{\left(8 x + \left(10 x^{3} + 81 x^{2}\right)\right) + 8}{x + 8} \geq 0$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\frac{\left(8 x + \left(10 x^{3} + 81 x^{2}\right)\right) + 8}{x + 8} = 0$$
Resolvemos:
$$x_{1} = - \frac{27}{10} - \frac{2107}{100 \left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}} - \frac{\left(- \frac{1}{2} - \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3}$$
$$x_{2} = - \frac{27}{10} - \frac{\left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{2107}{100 \left(- \frac{1}{2} + \frac{\sqrt{3} i}{2}\right) \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
$$x_{3} = - \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{27}{10} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
Descartamos las soluciones complejas:
$$x_{1} = - \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{27}{10} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
Las raíces dadas
$$x_{1} = - \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{27}{10} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} \leq x_{1}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{27}{10} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}\right) + - \frac{1}{10}$$
=
$$- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{14}{5} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
lo sustituimos en la expresión
$$\frac{\left(8 x + \left(10 x^{3} + 81 x^{2}\right)\right) + 8}{x + 8} \geq 0$$
$$\frac{\left(8 \left(- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{14}{5} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}\right) + \left(10 \left(- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{14}{5} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}\right)^{3} + 81 \left(- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{14}{5} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}\right)^{2}\right)\right) + 8}{\left(- \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{14}{5} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}\right) + 8} \geq 0$$
                                                                                    3                                                                                2                                                                          
          /                                                ________________________\       /                                                ________________________\                                              ________________________     
          |                                               /              _________ |       |                                               /              _________ |                                             /              _________      
          |                                              /  513081   3*\/ 2971194  |       |                                              /  513081   3*\/ 2971194  |                                            /  513081   3*\/ 2971194       
          |                                           3 /   ------ + ------------- |       |                                           3 /   ------ + ------------- |                                       8*3 /   ------ + -------------      
  72      |  14                  2107                 \/     1000          50      |       |  14                  2107                 \/     1000          50      |                  4214                   \/     1000          50           
- -- + 10*|- -- - --------------------------------- - -----------------------------|  + 81*|- -- - --------------------------------- - -----------------------------|  - -------------------------------- - -------------------------------     
  5       |  5             ________________________                 3              |       |  5             ________________________                 3              |            ________________________                  3                    
          |               /              _________                                 |       |               /              _________                                 |           /              _________                                        
          |              /  513081   3*\/ 2971194                                  |       |              /  513081   3*\/ 2971194                                  |          /  513081   3*\/ 2971194                                         
          |       100*3 /   ------ + -------------                                 |       |       100*3 /   ------ + -------------                                 |    25*3 /   ------ + -------------                                        
          \           \/     1000          50                                      /       \           \/     1000          50                                      /       \/     1000          50                                             
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >= 0
                                                                                                                                 ________________________                                                                                       
                                                                                                                                /              _________                                                                                        
                                                                                                                               /  513081   3*\/ 2971194                                                                                         
                                                                                                                            3 /   ------ + -------------                                                                                        
                                                                                   26                  2107                 \/     1000          50                                                                                             
                                                                                   -- - --------------------------------- - -----------------------------                                                                                       
                                                                                   5             ________________________                 3                                                                                                     
                                                                                                /              _________                                                                                                                        
                                                                                               /  513081   3*\/ 2971194                                                                                                                         
                                                                                        100*3 /   ------ + -------------                                                                                                                        
                                                                                            \/     1000          50                                                                                                                             
     

significa que la solución de la desigualdad será con:
$$x \leq - \frac{\sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}{3} - \frac{27}{10} - \frac{2107}{100 \sqrt[3]{\frac{3 \sqrt{2971194}}{50} + \frac{513081}{1000}}}$$
 _____          
      \    
-------•-------
       x1
Solución de la desigualdad en el gráfico
Respuesta rápida [src]
  /   /            /    3       2             \         \                     \
Or\And\x <= CRootOf\10*x  + 81*x  + 8*x + 8, 0/, -oo < x/, And(-8 < x, x < oo)/
$$\left(x \leq \operatorname{CRootOf} {\left(10 x^{3} + 81 x^{2} + 8 x + 8, 0\right)} \wedge -\infty < x\right) \vee \left(-8 < x \wedge x < \infty\right)$$
((-8 < x)∧(x < oo))∨((-oo < x)∧(x <= CRootOf(10*x^3 + 81*x^2 + 8*x + 8, 0)))
Respuesta rápida 2 [src]
             /    3       2             \            
(-oo, CRootOf\10*x  + 81*x  + 8*x + 8, 0/] U (-8, oo)
$$x\ in\ \left(-\infty, \operatorname{CRootOf} {\left(10 x^{3} + 81 x^{2} + 8 x + 8, 0\right)}\right] \cup \left(-8, \infty\right)$$
x in Union(Interval(-oo, CRootOf(10*x^3 + 81*x^2 + 8*x + 8, 0)), Interval.open(-8, oo))
Gráfico
(10x^3+81x^2+8x+8)/(x+8)>=0 desigualdades