Se da la desigualdad:
$$\left(x^{2} - 16\right) \log{\left(3 \right)}^{2} - 5 \frac{\log{\left(x^{2} - 16 \right)}}{\log{\left(3 \right)}} \geq 0$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\left(x^{2} - 16\right) \log{\left(3 \right)}^{2} - 5 \frac{\log{\left(x^{2} - 16 \right)}}{\log{\left(3 \right)}} = 0$$
Resolvemos:
$$x_{1} = - \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{2} = \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{3} = - \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{4} = \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{1} = - \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{2} = \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{3} = - \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{4} = \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
Las raíces dadas
$$x_{3} = - \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{1} = - \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{2} = \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x_{4} = \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} \leq x_{3}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{3} - \frac{1}{10}$$
=
$$- \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}} + - \frac{1}{10}$$
=
$$- \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}} - \frac{1}{10}$$
lo sustituimos en la expresión
$$\left(x^{2} - 16\right) \log{\left(3 \right)}^{2} - 5 \frac{\log{\left(x^{2} - 16 \right)}}{\log{\left(3 \right)}} \geq 0$$
/ 2 \
|/ ___________________________________\ |
|| / / 3 \ | |
/ 2 \ || / |-log (3) | 3 | |
|/ ___________________________________\ | || / - 5*W|---------, -1| + 16*log (3) | |
|| / / 3 \ | | || 1 \/ \ 5 / | |
|| / |-log (3) | 3 | | log||- -- - ----------------------------------------| - 16|
|| / - 5*W|---------, -1| + 16*log (3) | | || 10 3/2 | |
2 || 1 \/ \ 5 / | | \\ log (3) / /
log (3)*||- -- - ----------------------------------------| - 16| - 5*------------------------------------------------------------ >= 0
|| 10 3/2 | | 1
\\ log (3) / / log (3)
/ 2\
| / ___________________________________\ |
| | / / 3 \ | |
/ 2\ | | / |-log (3) | 3 | |
| / ___________________________________\ | | | / - 5*W|---------, -1| + 16*log (3) | |
| | / / 3 \ | | | | 1 \/ \ 5 / | |
| | / |-log (3) | 3 | | 5*log|-16 + |- -- - ----------------------------------------| | >= 0
| | / - 5*W|---------, -1| + 16*log (3) | | | | 10 3/2 | |
2 | | 1 \/ \ 5 / | | \ \ log (3) / /
log (3)*|-16 + |- -- - ----------------------------------------| | - ---------------------------------------------------------------
| | 10 3/2 | | log(3)
\ \ log (3) / /
significa que una de las soluciones de nuestra ecuación será con:
$$x \leq - \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
_____ _____ _____
\ / \ /
-------•-------•-------•-------•-------
x3 x1 x2 x4
Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x \leq - \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x \geq - \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}} \wedge x \leq \frac{\sqrt{- 5 W\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$
$$x \geq \frac{\sqrt{- 5 W_{-1}\left(- \frac{\log{\left(3 \right)}^{3}}{5}\right) + 16 \log{\left(3 \right)}^{3}}}{\log{\left(3 \right)}^{\frac{3}{2}}}$$