A. Rational Expressions

Rational expressions are similar to Rational Numbers; the main difference is that Rational Numbers are fractions made up of integers, while rational expressions are fractions made up of monomials and polynomials. Some examples of rational expressions are:

\[\frac{3x^2 - 4x}{2x},\thinspace \frac{7d^3}{9}, \thinspace \frac{25m^2 - 10mn + n^2}{5m - n}\]

Notice that given the definition of a rational expression, every polynomial is a rational expression with a denominator of one.

\[4x^2 - 9 = \frac{4x^2 - 9}{1}\]