\(\dfrac{3x^2-18}{2x^2+z}=0\)
\(\Leftrightarrow3x^2-18=0\)
\(\Leftrightarrow3x^2=18\)
\(\Leftrightarrow x^2=6\)
\(\Leftrightarrow x=\pm\sqrt{6}\)
Khi đó, \(2.6+z\ne0\)
\(\Leftrightarrow z\ne-12\)
Vậy \(\left\{{}\begin{matrix}x=\pm\sqrt{6}\\z\ne-12\end{matrix}\right.\) thì thoả mãn