Saturday, December 8, 2012

How do we rationalize a denominator?

Fractions are quite complicated. The denominator of a fractions is only limited to real integers. Having a radical as a denominator makes the fraction untrue, because it will be an irrational fraction. Therefore, we need to rationalize the denominator. Rationalizing the denominator means to simplify the fraction by getting rid of the radical sign.

How do you rationalize?
Easy! You rationalize the denominator by multiplying the denominator by its conjugate. A conjugate is when you change the sign of the binomial to get rid of the radical. For example:

Here, we need to rationalize the denominator therefore we multiply the√ ̅11 +2 by √ ̅11 -2. Remember whatever you multiply the denominator with you multiply the numerator as well! We multiply 3 by √ ̅11  -2 and viola! Your final answer is 3√ ̅ 11-6/7.


Try This:



Sources:

  • http://images.planetmath.org/cache/objects/8052/js/img1.png
  • http://tutorial.math.lamar.edu/Classes/Alg/Radicals_files/eq0085M.gif

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