\(\frac{13-x}{x+3}+\frac{6x^2+6}{x^4-8x^2-9}-\frac{3x+6}{x^2+5x+6}-\frac{2}{x-3}=0\)
\(\Leftrightarrow\frac{13-x}{x+3}+\frac{6x^2+6}{\left(x-3\right)\left(x+3\right)\left(x^2+1\right)}-\frac{3x+6}{\left(x+2\right)\left(x+3\right)}-\frac{2}{x-3}=0\)
\(\Leftrightarrow x^2-11x+30=0\)
\(\Leftrightarrow\left(x-6\right)\left(x-5\right)=0\)
\(\Leftrightarrow\left[\begin{matrix}x=6\\x=5\end{matrix}\right.\)