Results 1 to 3 of 3

Math Help - Expansion of brackets

  1. #1
    AS1
    AS1 is offline
    Newbie
    Joined
    Apr 2008
    Posts
    1

    Expansion of brackets

    Please help i need to expand and simplify (3x-y/3)^3

    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Mathstud28's Avatar
    Joined
    Mar 2008
    From
    Pennsylvania
    Posts
    3,641
    Quote Originally Posted by AS1 View Post
    Please help i need to expand and simplify (3x-y/3)^3

    the answer is <br />
x^3+x^2y+\frac{1}{3}xy^2+\frac{1}{27}y^3

    just expand it

    or use Pascal's Triangle


    Or use the Binomial theorem

    Mathstud..
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,914
    Thanks
    779
    Hello, AS1!

    Have you never cubed anything before?


    Expand and simplify: .(3x-y/3)^3
    I'm not sure exactly what the problem says.
    . . I'll do it both ways . . .


    \left(\frac{3x-y}{3}\right)^3 \;=\;\frac{(3x-y)^3}{3^3} \;= \;\frac{(3x)^3 - 3(3x)^2y + 3(3x)y^2 - y^3}{27}

    . . . . . . . = \;\frac{27x^3 - 27x^2y + 9xy^2 - y^3}{27}


    \left(3x-\frac{y}{3}\right)^3 \;=\;(3x)^3 - 3(3x)^2\left(\frac{y}{3}\right) + 3(3x)\left(\frac{y}{3}\right)^2 - \frac{y^3}{27}

    . . . . . . . = \;27x^3 - 9x^2y + xy^2 - \frac{y^3}{27}

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Brackets
    Posted in the Calculus Forum
    Replies: 4
    Last Post: November 21st 2010, 01:00 PM
  2. brackets
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: January 26th 2010, 01:19 PM
  3. brackets within brackets
    Posted in the Statistics Forum
    Replies: 11
    Last Post: October 4th 2009, 09:18 AM
  4. Replies: 6
    Last Post: May 1st 2009, 12:37 PM
  5. brackets expansion
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: July 28th 2008, 09:55 AM

Search Tags


/mathhelpforum @mathhelpforum