For polynomials P , Q ∈ R [ X ] {\displaystyle {}P,Q\in \mathbb {R} [X]} , Q ≠ 0 {\displaystyle {}Q\neq 0} , the function
where D {\displaystyle {}D} is the complement of the zeroes of Q {\displaystyle {}Q} , is called a rational function.
![{\displaystyle {}P,Q\in \mathbb {R} [X]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c0f5d5efbf99ce31e69814897dd026a6ef89c79a)
