# Rational Function

A rational function is a ratio of polynomials, such as $x_{3}+5x_{2}−3x_{2}−4x+1 $.

If the degree of numerator $≤$ degree denominator, then we can the rational function *proper*.

- if $<$, then
*strictly proper*

Else, we can it an *improper* rational function.

Note

Any proper rational function can be expressed as the sum of simpler rational functions, whose denominators are either linear or irreducibly quadratic.