Điều kiện: \(a;b\ne0\)
\(2a^2=9b\Rightarrow b=\frac{2}{9}a^2\)
\(\Delta=a^2-4b=a^2-\frac{8}{9}a^2=\frac{1}{9}a^2>0\)
\(\Rightarrow\) pt luôn có 2 nghiệm: \(\left\{{}\begin{matrix}x_1=-a+\frac{a}{3}=-\frac{2a}{3}\\x_2=-a-\frac{a}{3}=-\frac{4a}{3}\end{matrix}\right.\) \(\Rightarrow x_2=2x_1\)