Rational expression concepts -- introduction

The term “rational” in math is not used in the sense of “sane” or “sensible.” It is instead used to imply a ratio , or fraction. A rational expression is the ratio of two polynomials: for instance, $\frac{x^2+1}{x^2-1}$ is a rational expression.

There are two rules for working with rational expressions.

1. Begin every problem by factoring everything you can.
2. Remember that, despite all the complicated looking functions, a rational expression is just a fraction: you manipulate them using all the rules of fractions that you are familiar with.