Lesson 2

Lesson 2 Summary

 

In this lesson you investigated the following questions:

• How are multiplying and dividing rational expressions similar to multiplying and dividing rational numbers?
• How are non-permissible values determined when multiplying and dividing rational expressions?

In this lesson you learned about the similarities between multiplying and dividing rational expressions and multiplying and dividing rational numbers. In both cases, you must multiply numerators with numerators and denominators with denominators. At some point during the process, you must also simplify the result. You discovered that obtaining a simplified result is more easily done when the polynomial expressions in the numerator and denominator are first factored.

 

One aspect of multiplying and dividing rational expressions that does not emerge in multiplying and dividing rational numbers is the need to determine non-permissible values. You must identify those values of the variable(s) that would result in a 0 denominator as non-permissible.

 

When dividing rational expressions, you must also consider the numerator of the divisor or the second fraction. Since the numerator becomes the denominator in the course of division, you must also identify as non-permissible the value(s) of the variable(s) that would render the numerator equal to 0.

 

In the next lesson you will compare the addition and subtraction of rational expressions to the addition and subtraction of rational numbers.