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log(1/4)*(5*x-x^2)+(sqrt(5))^log(3)<0

log(1/4)*(5*x-x^2)+(sqrt(5))^log(3)<0 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
                           log(3)    
         /       2\     ___          
log(1/4)*\5*x - x / + \/ 5        < 0
$$\left(- x^{2} + 5 x\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} < 0$$
(-x^2 + 5*x)*log(1/4) + (sqrt(5))^log(3) < 0
Solución detallada
Se da la desigualdad:
$$\left(- x^{2} + 5 x\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} < 0$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\left(- x^{2} + 5 x\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} = 0$$
Resolvemos:
Abramos la expresión en la ecuación
$$\left(- x^{2} + 5 x\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} = 0$$
Obtenemos la ecuación cuadrática
$$2 x^{2} \log{\left(2 \right)} - 10 x \log{\left(2 \right)} + 5^{\frac{\log{\left(3 \right)}}{2}} = 0$$
Es la ecuación de la forma
a*x^2 + b*x + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = 2 \log{\left(2 \right)}$$
$$b = - 10 \log{\left(2 \right)}$$
$$c = 5^{\frac{\log{\left(3 \right)}}{2}}$$
, entonces
D = b^2 - 4 * a * c = 

(-10*log(2))^2 - 4 * (2*log(2)) * (5^(log(3)/2)) = 100*log(2)^2 - 8*5^(log(3)/2)*log(2)

Como D > 0 la ecuación tiene dos raíces.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

o
$$x_{1} = \frac{\sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{2} = \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{1} = \frac{\sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{2} = \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{1} = \frac{\sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{2} = \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
Las raíces dadas
$$x_{2} = \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
$$x_{1} = \frac{\sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
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
$$x_{0} = x_{2} - \frac{1}{10}$$
=
$$- \frac{1}{10} + \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
=
$$- \frac{1}{10} + \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
lo sustituimos en la expresión
$$\left(- x^{2} + 5 x\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} < 0$$
$$\left(- \left(- \frac{1}{10} + \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}\right)^{2} + 5 \left(- \frac{1}{10} + \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}\right)\right) \log{\left(\frac{1}{4} \right)} + \left(\sqrt{5}\right)^{\log{\left(3 \right)}} < 0$$
          /                                                                  2                                                          \           
          |      /              ________________________________            \      /       ________________________________            \|           
          |      |             /                  log(3)                    |      |      /                  log(3)                    ||           
 log(3)   |      |            /                   ------                    |      |     /                   ------                    ||           
 ------   |      |           /          2           2                       |      |    /          2           2                       ||        < 0
   2      |  1   |  1    - \/    100*log (2) - 8*5      *log(2)  + 10*log(2)|    5*\- \/    100*log (2) - 8*5      *log(2)  + 10*log(2)/|           
5       - |- - - |- -- + ---------------------------------------------------|  + -------------------------------------------------------|*log(4)    
          \  2   \  10                         4*log(2)                     /                            4*log(2)                       /           
    

pero
          /                                                                  2                                                          \           
          |      /              ________________________________            \      /       ________________________________            \|           
          |      |             /                  log(3)                    |      |      /                  log(3)                    ||           
 log(3)   |      |            /                   ------                    |      |     /                   ------                    ||           
 ------   |      |           /          2           2                       |      |    /          2           2                       ||        > 0
   2      |  1   |  1    - \/    100*log (2) - 8*5      *log(2)  + 10*log(2)|    5*\- \/    100*log (2) - 8*5      *log(2)  + 10*log(2)/|           
5       - |- - - |- -- + ---------------------------------------------------|  + -------------------------------------------------------|*log(4)    
          \  2   \  10                         4*log(2)                     /                            4*log(2)                       /           
    

Entonces
$$x < \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x > \frac{- \sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}} \wedge x < \frac{\sqrt{- 8 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} \log{\left(2 \right)} + 100 \log{\left(2 \right)}^{2}} + 10 \log{\left(2 \right)}}{4 \log{\left(2 \right)}}$$
         _____  
        /     \  
-------ο-------ο-------
       x2      x1
Solución de la desigualdad en el gráfico
Respuesta rápida [src]
   /             _________________________           _________________________    \
   |            /      log(3)                       /      log(3)                 |
   |           /       ------                      /       ------                 |
   |          /          2                        /          2                    |
   |    5   \/    - 2*5       + 25*log(2)   5   \/    - 2*5       + 25*log(2)     |
And|x < - + ------------------------------, - - ------------------------------ < x|
   |    2                ________           2                ________             |
   \                 2*\/ log(2)                         2*\/ log(2)              /
$$x < \frac{\sqrt{- 2 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} + 25 \log{\left(2 \right)}}}{2 \sqrt{\log{\left(2 \right)}}} + \frac{5}{2} \wedge - \frac{\sqrt{- 2 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} + 25 \log{\left(2 \right)}}}{2 \sqrt{\log{\left(2 \right)}}} + \frac{5}{2} < x$$
(x < 5/2 + sqrt(-2*5^(log(3)/2) + 25*log(2))/(2*sqrt(log(2))))∧(5/2 - sqrt(-2*5^(log(3)/2) + 25*log(2))/(2*sqrt(log(2))) < x)
Respuesta rápida 2 [src]
          _________________________           _________________________ 
         /      log(3)                       /      log(3)              
        /       ------                      /       ------              
       /          2                        /          2                 
 5   \/    - 2*5       + 25*log(2)   5   \/    - 2*5       + 25*log(2)  
(- - ------------------------------, - + ------------------------------)
 2                ________           2                ________          
              2*\/ log(2)                         2*\/ log(2)           
$$x\ in\ \left(- \frac{\sqrt{- 2 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} + 25 \log{\left(2 \right)}}}{2 \sqrt{\log{\left(2 \right)}}} + \frac{5}{2}, \frac{\sqrt{- 2 \cdot 5^{\frac{\log{\left(3 \right)}}{2}} + 25 \log{\left(2 \right)}}}{2 \sqrt{\log{\left(2 \right)}}} + \frac{5}{2}\right)$$
x in Interval.open(-sqrt(-2*5^(log(3)/2) + 25*log(2))/(2*sqrt(log(2))) + 5/2, sqrt(-2*5^(log(3)/2) + 25*log(2))/(2*sqrt(log(2))) + 5/2)
Gráfico
log(1/4)*(5*x-x^2)+(sqrt(5))^log(3)<0 desigualdades