Find Two Paths of Approach from Which One Can Conclude $$f ( x , y ) = \frac { x y } { x ^ { 2 } + y ^ { 2 } }$$

Essay

Find two paths of approach from which one can conclude that the function has no limit as (x, y) approaches (0, 0).
- $$f ( x , y ) = \frac { x y } { x ^ { 2 } + y ^ { 2 } }$$