This chapter deals with rational expressions; that is, with 
expressions whose numerators and denominators are (or can be written 
as) polynomials.
The first section explains how to write a rational expression in 
lowest terms by 
factoring the numerator and the denominator.  
We write rational expressions in lowest terms in order to work with them 
more easily.  In addition, writing rational expressions in lowest terms 
allows us to recognize equivalent expressions.
The second section explains how to add and subtract rational 
expressions.  The process by which we add and subtract rational 
expressions is similar to the process by which we add and subtract 
constant fractions.
The next logical step after learning how to add and subtract rational 
expressions is learning how to multiply and divide rational 
expressions.  This is the focus of section three.  
The final section explains how to solve rational equations.  A rational 
equation is formed by setting two rational expressions equal to each 
other.  Solving rational equations is slightly different from solving 
polynomial equations in that we may come up with solutions which 
produce zero in a denominator.  Since we cannot divide by zero, these 
solutions must be discarded.
Like polynomials, rational expressions appear frequently 
in Algebra II and higher mathematics.  Thus, we 
must understand how to perform basic operations with rational expressions 
and how to solve rational equations.