1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Rationalizing the denominator

  1. May 26, 2010 #1
    1. The problem statement, all variables and given/known data

    I am confused with this equation I found online... It seems wrong to me, I need help.
    My question is,why did the person who worked taht equation use a x^2 to rationalize the equation when the actual equation was an x^3??
    http://tutorial.math.lamar.edu/Classes/Alg/Radicals_files/eq0081MP.gif
    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 26, 2010 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Because the fifth root of x^2*x^3=x^5 is x. How would you do it??
     
  4. May 26, 2010 #3
    no my question is... why was x^2 used instead of x^3 to rationalize the denominator? my thinking is if x^2 is the denominator then why use x^3 to rationalize it?
     
  5. May 27, 2010 #4

    HallsofIvy

    User Avatar
    Science Advisor

    Because [itex]x^2*x^3= x^5[/itex] as Dick said. The crucial point is that it is the fifth root that is to be rationalized. You have to multiply what ever power is necessary to get a fifth power inside the fifth root.

    In general to rationalize the denominator of [itex]1/\sqrt[n]{x^m}[/itex] you need to multiply numerator and denominator by [itex]\sqrt[n]{x^{n-m}}[/itex]. That way, in the denominator you will have [itex]\sqrt[n]{x^nx^{n-m}}= \sqrt[n]{x^n}= x[/itex].
     
  6. May 27, 2010 #5
    I get it now thanks..
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook