Rationalizing the Denominator

Definition of Rationalizing the Denominator

  • Rationalizing the denominator is the process by which a fraction containing radicals in the denominator is rewritten to have only rational numbers in the denominator.
 

Examples of Rationalizing the Denominator

In the example above, the radical  in the denominator is converted into a rational number by multiplying and dividing the fraction by  using the fact that . This process is called ‘rationalizing the denominator.’

Here  in the denominator is converted into a rational number by multiplying and dividing the fraction by the conjugate  using the fact that .

Solved Example on Rationalizing the Denominator

Simplify  by rationalizing the denominator.

Choices:

A.

B.

C.

D.

Correct answer: D

Solution:

Step 1:                         [Use quotient property.]

Step 2:                                                       [Use product property.]

Step 3:                                                             []

Step 4:                                           [Multiply by a value of  = 1.]

Step 5:

                                 

Related Terms for Rationalizing the Denominator

  • Denominator
  • Rational Number
  • Fraction

                                                

Additional Links for Rationalizing the Denominator