\(\Leftrightarrow1-\frac{6}{x^2+2}+1-\frac{12}{x^2+8}+1-\frac{7}{x^2+3}=0\)
\(\Leftrightarrow\frac{x^4-4}{x^2+2}+\frac{x^2-4}{x^2+8}+\frac{x^2-4}{x^2+3}=0\)
\(\Leftrightarrow\left(x^2-4\right)\left(\frac{1}{x^2+2}+\frac{1}{x^2+8}+\frac{1}{x^2+2}\right)=0\)
\(\Leftrightarrow x^2-4=0\Rightarrow x=\pm2\)