Q$1)f(x,y)=\{\begin{array}{ccc}\frac{y^2}{x^{2}y+x^4}\text{;},& \text{;}(x,y)(0,& 0)\\ 0\text{;},& \text{;}(x,y)=(0,& 0)\end{array}$

$\underset{?}{lim}f(x,y)=?$

$(x,y)(0,0)$

Is $f(x,y)$ continuous at $(0,0)=?$