**A Rational Expression** is the quotient of two polynomials and with .

Ex.
.

**Lowest Terms of a Rational Expression** A rational expression is written in lowest terms when the greatest common factor of its numerator and denominator is 1.

__Remark__ To write a rational expression in lowest terms we use the basic principle of fractions:
, (, ).

Ex.
.

**Operations of Rational Expressions**
For fractions
and
(, ),

__Multiplication and Division:__
, and

__Addition and Subtraction:__
and
.

**The Least Common Denominator (LCD)** of two rational expressions:

Ex. The LCD of
and
is
.

**A complex fraction** is the quotient of two rational expressions.

Ex.

Department of Mathematics