For what points is the function continuous?

$\displaystyle f(x,y)=\frac{xy}{x^2-y}$

Intuition tells me that it would be continuous everywhere except where the denominator equals zero so... Would it be continuous everywhere except on the parabola $\displaystyle y=x^2$?

Also

$\displaystyle f(x,y)=\frac{x^4-4y^4}{x^2+2y^2}$

Find the limit of $\displaystyle f(x,y)$ as $\displaystyle (x,y)\rightarrow(0,0)$

Thanks for the help.(Happy)