9. Passing through the point $(2,-2)$, and having common asymptotes with the hyperbola $x^{2}-2 y^{2}=2$, the equation of the hyperbola is
9. $\frac{y^{2}}{2}-\frac{x^{2}}{4}=1$. Hint: The equation can be set as $x^{2}-2 y^{2}=\lambda$, substitute $(2,-2)$ into the equation.