IX. (1) Suppose that there are two parallel planes $$ X-2 y-2 z=5, X-2 y-2 z=8 \text {. } $$ Find the distance between them. (2) Sketch the rough graph of the following quadric surface: $$ \frac{x^{2}}{16}+\frac{y^{2}}{4}+\frac{z^{2}}{36}=1 \text {. } $$ X. Show that the limit $\lim _{(x, y) ightarrow 0,0)} \frac{x^{4}+2 y^{4}} {x^{4}+y^{4}}$ does not exist. CS. JG. 103