\text { Show that the limit } \lim _{(x, y) \rightarrow(0.0)} \frac{x^{2} y \cos (y)}{x^{6}+v^{2}} \text { does not exist. Also, if } \text { possible, find } \lim _{(x, y) \rightarrow(-2,1)} \frac{x^{3}+8 y^{3}}{3 x^{2}-12 y^{2}}