Results 1 to 4 of 4

Math Help - Simplyfing a simple equation: (18 - 2a)^2

  1. #1
    Newbie
    Joined
    Apr 2008
    Posts
    2

    [Solved] Simplyfing a simple equation: (18 - 2a)^2

    This is what I need to Simplify: (18 - 2a)

    The lecturer briefly mentioned that (18 - 2a) = 18 x 2a, but I think he made an error? I don't know how he got to that answer. Substituting a value for "a" afterwards shows that it's wrong.

    This is what I've done, using what I thought were normal techniques, but again substituting values for "a" afterwards shows that it's wrong too:

    (18 - 2a)
    = (18 - 2a)*(18 - 2a)
    = 18(18 - 2a) - 2a(18 - 2a)
    = 324 - 36a - 36a + 2a.
    = 324 - 72a + 2a.

    Any help appreciated.

    Thanks
    Last edited by Timo; April 29th 2008 at 02:17 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Lord of certain Rings
    Isomorphism's Avatar
    Joined
    Dec 2007
    From
    IISc, Bangalore
    Posts
    1,465
    Thanks
    6
    Quote Originally Posted by Timo View Post
    This is what I need to Simplify: (18 - 2a)

    The lecturer briefly mentioned that (18 - 2a) = 18 x 2a, but I think he made an error? I don't know how he got to that answer.

    This is what I've done, using what I thought were normal techniques, but again substituting values for "a" afterwards shows that it's wrong:

    (18 - 2a)
    = (18 - 2a)*(18 - 2a)
    = 18(18 - 2a) - 2a(18 - 2a)
    The next step is
    = 324 - 36a - 36a + 4a.

    Thats the only mistake
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member Danshader's Avatar
    Joined
    Mar 2008
    From
    http://en.wikipedia.org/wiki/Malaysia now stop asking me where is malaysia...
    Posts
    158
    you are suppose to get:

    (18-2a)^2<br />
= 18^2 - 72a + 4a^2<br />
= 324 - 72a + 4a^2<br />
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Apr 2008
    Posts
    2
    Nailed it! Thanks ever so much, both.

    Means the lecturer was way out, too.

    Cheers!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Simplyfing dificulties
    Posted in the Algebra Forum
    Replies: 5
    Last Post: November 3rd 2010, 04:51 PM
  2. Replies: 1
    Last Post: August 24th 2010, 11:46 PM
  3. simplyfing expressions?
    Posted in the Algebra Forum
    Replies: 1
    Last Post: January 12th 2010, 04:09 PM
  4. simplyfing radical
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: April 6th 2009, 12:10 PM
  5. Simplyfing algebraic expressions
    Posted in the Algebra Forum
    Replies: 1
    Last Post: April 11th 2007, 07:16 PM

Search Tags


/mathhelpforum @mathhelpforum