# Simplify rational expression

An algebraic expression where both the numerator and the denominator are polynomials e.g.

is called a rational expression. Since the denominator can't be zero there are values of x which are excluded from the rational expression. The expression above has an excluded value of zero.

To simplify a rational expression you have to eliminate all factors that are common of the numerator and the denominator. To accomplish this use the greatest common factor (GCF) of the factors e.g.

**Video lesson:** Simplify rational expression

**Rational expressions, Multiply rational expressions**