1 reply to this topic

[pndpnd]

Giải:

$2\sqrt{\frac{9}{x^2}+x+6}+x-1=0$ với $x<0$

Edited by pndpnd, 23-05-2016 - 10:47.

[Shin Janny]

Giải:

$2\sqrt{\frac{9}{x^2}+x+6}+x-1=0$ với $x<0$

$\Leftrightarrow x+3+2(\sqrt{\frac{9}{x^{2}}+x+6}-2)=0$

$\Leftrightarrow x+3+2.\frac{\frac{9+x^{3}+6x^{2}}{x^{2}}-4}{\sqrt{\frac{9}{x^{2}}+x+6}+2}=0$

$\Leftrightarrow (x+3)(1+2.\frac{x^{2}-x+3}{x^{2}(\sqrt{\frac{9}{x^{2}+x+6}}+2)})=0$

$\Leftrightarrow x=-3$

Edited by Shin Janny, 23-05-2016 - 11:32.