Explain Simplifying Rational Expressions ?

A rational expression, or algebraic fraction, is an expression in which you have a polynomial divided by a polynomial. Sometimes it is said that a rational expression is a polynomial "over" a polynomial.

Here are two examples of rational expressions:

10x³y/15x²y⁴ and (2x² +11x +15) /x²-9

Important: The bottom polynomial can never be zero, because division by zero is undefined!
To simplify or reduce a fraction such as 6/15, you must first factor the numerator and denominator, and then you can eliminate, or cross out, the common factors.

Like this:

The same canceling procedure can be used to simplify rational expressions. Here are some examples of how you can do this: