Results 1 to 4 of 4

Math Help - Stuck again :(

  1. #1
    Junior Member
    Joined
    Sep 2009
    Posts
    27

    Stuck again :(

    4√(5*x^8*y^3)/(27*x^2)

    Need to simplify and rationalize the denominator.

    Just a little confused where to start, i already seperated the top and bottom of the brackets and each individual thing inside. And the first *4√* being "fourth root"
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Hello Djaevel
    Quote Originally Posted by Djaevel View Post
    4√(5*x^8*y^3)/(27*x^2)

    Need to simplify and rationalize the denominator.

    Just a little confused where to start, i already seperated the top and bottom of the brackets and each individual thing inside. And the first *4√* being "fourth root"
    Since you talk about rationalising the denominator, I assume that you mean \sqrt[4]{\frac{5x^8y^3}{27x^2}} and not \frac{\sqrt[4]{5x^8y^3}}{27x^2} (which is what you've written). So, study what I've done here carefully - I've used the rules of indices (and the fact that 3^3=27):

    \sqrt[4]{\frac{5x^8y^3}{27x^2}}=\frac{\sqrt[4]{5}\sqrt[4]{x^8}\sqrt[4]{y^3}}{\sqrt[4]{27}\sqrt[4]{x^2}}

    =\frac{5^{\frac14}x^2y^{\frac34}}{27^{\frac14}x^{\  frac12}}

    =\frac{5^{\frac14}x^{\frac32}y^{\frac34}}{3^{\frac  34}}\times\frac{3^{\frac14}}{3^{\frac14}}

    =\frac{5^{\frac14}3^{\frac14}x^{\frac32}y^{\frac34  }}{3^{\frac34}3^{\frac14}}

    =\frac{15^{\frac14}x^{\frac32}y^{\frac34}}{3}

    Grandad
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Sep 2009
    Posts
    27
    Alright that makes tons of sense. I just havent done any of this math in a long while and im a whole lot rusty.

    Only thing that im stuck on is that its supossed to be X/3 4√15*x^2*y^3

    I get where i get the x/3 from, but the x^2 under the 4th root i do not. And i get where the 4th root comes from.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Hello Djaevel
    Quote Originally Posted by Djaevel View Post
    Alright that makes tons of sense. I just havent done any of this math in a long while and im a whole lot rusty.

    Only thing that im stuck on is that its supossed to be X/3 4√15*x^2*y^3

    I get where i get the x/3 from, but the x^2 under the 4th root i do not. And i get where the 4th root comes from.
    Continuing from the answer I gave:

    \frac{15^{\frac14}x^{\frac32}y^{\frac34}}{3}


    = \frac{\sqrt[4]{15\,x^{(4\times\frac32)}\,y^{(4\times\frac34)}}}{  3}

    = \frac{\sqrt[4]{15\,x^6\,y^3}}{3}

    = \frac{\sqrt[4]{15\,x^4\,x^2\,y^3}}{3}

    = \frac{x}{3}\sqrt[4]{15\,x^2\,y^3}

    Grandad
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Stuck
    Posted in the Algebra Forum
    Replies: 6
    Last Post: January 21st 2010, 11:09 AM
  2. stuck with sin^4(x)
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 24th 2009, 04:56 PM
  3. Stuck on a Log :(
    Posted in the Algebra Forum
    Replies: 9
    Last Post: January 21st 2008, 12:10 PM
  4. somebody help me plz im so stuck
    Posted in the Math Topics Forum
    Replies: 4
    Last Post: September 30th 2007, 11:43 AM
  5. Stuck, Stuck, Stuck - Need Help Urgently
    Posted in the Algebra Forum
    Replies: 3
    Last Post: May 17th 2005, 05:46 AM

Search Tags


/mathhelpforum @mathhelpforum