#[Rational expression][Expresión racional]#
A rational expression is an algebraic expression of the form $\dfrac{P}{Q},$ where $P$ and $Q$ are simpler expressions (usually polynomials), and the denominator $Q$ is not zero.
Examples
$\dfrac{1}{x-1}$ \t \gap[40] \t is rational with $\color{slateblue}{P = 1,\ \ Q = x-1}$
\\ $\dfrac{x^2+3x+1}{x^2+3}$ \t \t is rational with $\color{slateblue}{P = x^2+3x+1,\ \ Q = x^2+3}$
\\ $x^2 = \dfrac{x^2}{1}$ \t \t can be thought of as rational with $\color{slateblue}{P = x^2},$ and $\color{slateblue}{Q = 1}.$