What are the asymptotes for the hyperbola
\frac{x^2}{a^2}- \frac{y^2}{b^2}= 1?
Can you put your equation in that form?
Another way to do this: The hyperbola comes close to the asymptote for VERY large values of x and y. Rewrite the equation as 6x^2= dy^2+ 6. Suppose x and y are in the tens of millions. How does the constant "6" compare with the rest of the equation?