Find Two Paths of Approach from Which One Can Conclude $\text { Show that } f ( x , y , z ) = e ^ { x ^ { 2 } + y ^ { 2 } + z ^ { 2 } } \text { is continuous at the origin. }$

Essay

Find two paths of approach from which one can conclude that the function has no limit as (x, y) approaches (0, 0).
- $\text { Show that } f ( x , y , z ) = e ^ { x ^ { 2 } + y ^ { 2 } + z ^ { 2 } } \text { is continuous at the origin. }$