What Is the Domain Of $f ( x , y ) = \frac { x } { \left( x ^ { 2 } + y ^ { 2 } - 64 \right) ^ { 1 / 2 } }$

Short Answer

What is the domain of $f ( x , y ) = \frac { x } { \left( x ^ { 2 } + y ^ { 2 } - 64 \right) ^ { 1 / 2 } }$ ?