Results 1 to 3 of 3

Math Help - Radical Exoressions

  1. #1
    Newbie
    Joined
    Dec 2011
    Posts
    10

    Radical Exoressions

    the square root of x+120 minus the square root of x+3 is equal to 9.


    I got confused on simplifying part because I didnt get it to match 5 which is the answer.



    If you can show me how to solve this the proper way please and how to post problems in here with square root signs and divsions and fractions please

    Thank you!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,959
    Thanks
    1781
    Awards
    1

    Re: Radical Exoressions

    Quote Originally Posted by daword177 View Post
    the square root of x+120 minus the square root of x+3 is equal to 9.
    If you can show me how to solve this the proper way please and how to post problems in here with square root signs and divsions and fractions please.
    Use LaTeX code: [TEX]\sqrt{x+120}-\sqrt{x+3}=9[/TEX] gives \sqrt{x+120}-\sqrt{x+3}=9

    Add to both sides \sqrt{x+120}=9+\sqrt{x+3}
    Square both sides {x+120}=81+18\sqrt{x+3}+(x+3).
    Combine terms {36}=18\sqrt{x+3}
    Divide to get \sqrt{x+3}=2
    Finish.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Apr 2005
    Posts
    16,400
    Thanks
    1849

    Re: Radical Exoressions

    Note that x is NOT equal to 5. If x= 5, then \sqrt{x+ 120}= \sqrt{5+ 120}= \sqrt{125}= 5\sqrt{5} and \sqrt{x+ 3}= \sqrt{5+ 3}= \sqrt{8}= 2\sqrt{2}. \sqrt{x+120}- \sqrt{x+ 3}= 5\sqrt{5}- 2\sqrt{2}\ne 9.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Ring isomorphism maps a Jacobson radical into a Jacobson radical?
    Posted in the Advanced Algebra Forum
    Replies: 4
    Last Post: June 21st 2010, 11:45 AM
  2. Radical
    Posted in the Algebra Forum
    Replies: 1
    Last Post: November 25th 2009, 06:37 AM
  3. Radical-Radical equation
    Posted in the Algebra Forum
    Replies: 6
    Last Post: June 27th 2009, 04:38 AM
  4. Radical
    Posted in the Algebra Forum
    Replies: 3
    Last Post: September 23rd 2008, 09:00 AM
  5. Radical inside a radical?
    Posted in the Algebra Forum
    Replies: 3
    Last Post: March 14th 2007, 10:59 PM

Search Tags


/mathhelpforum @mathhelpforum