Results 1 to 2 of 2

Math Help - Algebra (Discrete Mathematics)

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    24

    Algebra (Discrete Mathematics)

    Hi.. I'm following along in a book for my Discrete Mathematics class and I'm having trouble finding out what's going on between two steps algebraically.

    21-1(77-3 x 21)
    = 4 x 21 - 1 x 77

    Exactly what is happening between these two steps? I can't see where the 4 comes from.

    (Note: The xs in this problem stand for multiplication, not a variable x)


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

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by kwikness View Post
    Hi.. I'm following along in a book for my Discrete Mathematics class and I'm having trouble finding out what's going on between two steps algebraically.

    21-1(77-3 x 21)
    = 4 x 21 - 1 x 77

    Exactly what is happening between these two steps? I can't see where the 4 comes from.

    (Note: The xs in this problem stand for multiplication, not a variable x)


    Thank you.
    21 - (77 - 3x21) = 21 - 77 + 3x21 .....by multiplying out so as to expand the brackets

    now we have 1 21 in front and 3 21's in the back. together, we hae 4 21's

    so we get 4x21 - 77 or 4x21 - 1x77
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Calculus and discrete mathematics
    Posted in the Higher Math Forum
    Replies: 5
    Last Post: October 11th 2011, 04:43 PM
  2. discrete mathematics
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: October 1st 2010, 06:39 PM
  3. What is discrete Mathematics About ?
    Posted in the Discrete Math Forum
    Replies: 7
    Last Post: June 4th 2009, 10:28 PM
  4. Mathematics: Discrete-Mathematics (Algorithems)
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: November 2nd 2008, 07:27 AM
  5. discrete mathematics..help!!!!!
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: September 12th 2008, 05:43 AM

Search Tags


/mathhelpforum @mathhelpforum