\(\Leftrightarrow3x-6+\sqrt{x^2+5}-3+4-\sqrt{x^2+12}\ge0\)
\(\Leftrightarrow3\left(x-2\right)+\frac{x^2-4}{\sqrt{x^2+5}+3}-\frac{x^2-4}{\sqrt{x^2+12}+4}\ge0\)
\(\Leftrightarrow\left(x-2\right)\left(3+\frac{x+2}{\sqrt{x^2+5}+3}-\frac{x+2}{\sqrt{x^2+12}+4}\right)\ge0\)
\(\Leftrightarrow x-2\ge0\Rightarrow x\ge2\)