Results 1 to 5 of 5

Math Help - x = 9 times the square root of x

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    2

    x = 9 times the square root of x

    Can someone help me with this problem? I do not know how to work it...

    x = 9 (the square root of x)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Banned
    Joined
    Sep 2008
    Posts
    34
    x = 9*sqrt(x) => x^2 = 81x

    which gives x^2 - 81x = 0

    or

    x(x - 81) = 0

    x= 0, 81
    Follow Math Help Forum on Facebook and Google+

  3. #3
    TMU
    TMU is offline
    Newbie
    Joined
    Sep 2008
    Posts
    3
    The square root of x = 9

    If that's what you're asking for then it's simply 9^2 which is 81.
    So the square root of 81 = 9.

    If that's not what you're asking for, then sorry I dont full understand what you're asking.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Sep 2008
    Posts
    2
    Quote Originally Posted by damadama View Post
    x = 9*sqrt(x) => x^2 = 81x

    which gives x^2 - 81x = 0

    or

    x(x - 81) = 0

    x= 0, 81
    Ahh... this is it. Thanks for the explanation.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,186
    Thanks
    404
    Awards
    1
    Quote Originally Posted by TMU View Post
    The square root of x = 9

    If that's what you're asking for then it's simply 9^2 which is 81.
    So the square root of 81 = 9.

    If that's not what you're asking for, then sorry I dont full understand what you're asking.
    The reason you missed the x = 0 solution is that you divided both sides by \sqrt{x} which is an invalid procedure when x = 0.

    Tip: When you are dividing both sides of an equation always remember to set that factor equal to 0 to see if there might be another solution in there.

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Square root inside square root equation
    Posted in the Algebra Forum
    Replies: 3
    Last Post: October 10th 2011, 05:17 PM
  2. square root + cube root of a number
    Posted in the Algebra Forum
    Replies: 2
    Last Post: December 5th 2010, 11:35 AM
  3. Replies: 12
    Last Post: November 22nd 2008, 01:41 PM
  4. Simplifying Square Root w/in square root
    Posted in the Algebra Forum
    Replies: 5
    Last Post: September 7th 2006, 09:01 AM
  5. Replies: 2
    Last Post: April 29th 2006, 02:13 AM

Search Tags


/mathhelpforum @mathhelpforum