ĐKXĐ:\(\left\{{}\begin{matrix}2x-6\ne0\\x^2-9\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x-3\ne0\\x^2\ne9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne3\\x\ne\pm3\end{matrix}\right.\Leftrightarrow x\ne\pm3\)
\(\dfrac{x}{2x-6}-\dfrac{4}{x^2-9}=0\\ \Leftrightarrow\dfrac{x}{2\left(x-3\right)}-\dfrac{4}{\left(x-3\right)\left(x+3\right)}=0\\ \Leftrightarrow\dfrac{x\left(x+3\right)}{2\left(x-3\right)\left(x+3\right)}-\dfrac{8}{2\left(x-3\right)\left(x+3\right)}=0\\ \Leftrightarrow\dfrac{x^2+3x-8}{2\left(x-3\right)\left(x+3\right)}=0\\ \Leftrightarrow x^2+3x-8=0\)
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