Se da la desigualdad:
$$- \sqrt[4]{\frac{12 x}{x - 2}} + \left(\frac{6 x}{x - 2} - \sqrt{\frac{12 x}{x - 2}}\right) > 0$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$- \sqrt[4]{\frac{12 x}{x - 2}} + \left(\frac{6 x}{x - 2} - \sqrt{\frac{12 x}{x - 2}}\right) = 0$$
Resolvemos:
$$x_{1} = 0$$
$$x_{2} = \frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}$$
$$x_{1} = 0$$
$$x_{2} = \frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}$$
Las raíces dadas
$$x_{2} = \frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}$$
$$x_{1} = 0$$
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
$$x_{0} = x_{2} - \frac{1}{10}$$
=
$$\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} + - \frac{1}{10}$$
=
$$\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}$$
lo sustituimos en la expresión
$$- \sqrt[4]{\frac{12 x}{x - 2}} + \left(\frac{6 x}{x - 2} - \sqrt{\frac{12 x}{x - 2}}\right) > 0$$
$$- \sqrt[4]{\frac{12 \left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right)}{\left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right) - 2}} + \left(- \sqrt{\frac{12 \left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right)}{\left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right) - 2}} + \frac{6 \left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right)}{\left(\frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}} - \frac{1}{10}\right) - 2}\right) > 0$$
4
/ ___________________________ \
| / ___ 4 ___ 3/4 ____ ___ |
| / \/ 2 *\/ 3 3 *\/ 38 \/ 3 |
12*|3 / ----------- + ----------- + ----------------------------------|
|\/ 12 108 ___________________________|
| / ___ 4 ___ 3/4 ____ |
| / \/ 2 *\/ 3 3 *\/ 38 |
| 9*3 / ----------- + ----------- |
3 \ \/ 12 108 /
- - + ----------------------------------------------------------------------------- ___________________________________________________________________________________ ___________________________________________________________________________________
5 4 / 4 / 4
/ ___________________________ \ / / ___________________________ \ / / ___________________________ \
| / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ |
| / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 |
-1 + |3 / ----------- + ----------- + ----------------------------------| / 24*|3 / ----------- + ----------- + ----------------------------------| / 24*|3 / ----------- + ----------- + ----------------------------------|
|\/ 12 108 ___________________________| / |\/ 12 108 ___________________________| / |\/ 12 108 ___________________________|
| / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ |
| / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 |
| 9*3 / ----------- + ----------- | ______________________________________________________________________________________ / | 9*3 / ----------- + ----------- | ______________________________________________________________________________________ / | 9*3 / ----------- + ----------- |
\ \/ 12 108 / / -1 / 6 \ \/ 12 108 / / -1 / 6 \ \/ 12 108 /
------------------------------------------------------------------------------------ - / ------------------------------------------------------------------------------------ * / - - ----------------------------------------------------------------------------- - / ------------------------------------------------------------------------------------ * / - - ----------------------------------------------------------------------------- > 0
4 / 4 / 5 4 / 4 / 5 4
/ ___________________________ \ / / ___________________________ \ / / ___________________________ \ / / ___________________________ \ / / ___________________________ \
| / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ |
| / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 |
2*|3 / ----------- + ----------- + ----------------------------------| / 2*|3 / ----------- + ----------- + ----------------------------------| / -1 + |3 / ----------- + ----------- + ----------------------------------| / 2*|3 / ----------- + ----------- + ----------------------------------| / -1 + |3 / ----------- + ----------- + ----------------------------------|
|\/ 12 108 ___________________________| / |\/ 12 108 ___________________________| / |\/ 12 108 ___________________________| / |\/ 12 108 ___________________________| / |\/ 12 108 ___________________________|
| / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ |
| / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 |
| 9*3 / ----------- + ----------- | / | 9*3 / ----------- + ----------- | / | 9*3 / ----------- + ----------- | / | 9*3 / ----------- + ----------- | 4 / | 9*3 / ----------- + ----------- |
21 \ \/ 12 108 / / 21 \ \/ 12 108 / \/ \ \/ 12 108 / / 21 \ \/ 12 108 / \/ \ \/ 12 108 /
- -- + ----------------------------------------------------------------------------- / - -- + ----------------------------------------------------------------------------- / - -- + -----------------------------------------------------------------------------
10 4 / 10 4 / 10 4
/ ___________________________ \ / / ___________________________ \ / / ___________________________ \
| / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ | / | / ___ 4 ___ 3/4 ____ ___ |
| / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 | / | / \/ 2 *\/ 3 3 *\/ 38 \/ 3 |
-1 + |3 / ----------- + ----------- + ----------------------------------| / -1 + |3 / ----------- + ----------- + ----------------------------------| / -1 + |3 / ----------- + ----------- + ----------------------------------|
|\/ 12 108 ___________________________| / |\/ 12 108 ___________________________| / |\/ 12 108 ___________________________|
| / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ | / | / ___ 4 ___ 3/4 ____ |
| / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 | / | / \/ 2 *\/ 3 3 *\/ 38 |
| 9*3 / ----------- + ----------- | / | 9*3 / ----------- + ----------- | 4 / | 9*3 / ----------- + ----------- |
\ \/ 12 108 / \/ \ \/ 12 108 / \/ \ \/ 12 108 /
significa que una de las soluciones de nuestra ecuación será con:
$$x < \frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}$$
_____ _____
\ /
-------ο-------ο-------
x2 x1
Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x < \frac{2 \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}{-1 + \left(\frac{\sqrt{3}}{9 \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}} + \sqrt[3]{\frac{2^{\frac{3}{4}} \cdot 3 \sqrt{38} \sqrt[4]{54}}{648} + \frac{\sqrt{2} \sqrt[4]{3}}{12}}\right)^{4}}$$
$$x > 0$$