Results 1 to 3 of 3

Math Help - what is a triangular number ?

  1. #1
    Newbie
    Joined
    Oct 2008
    Posts
    1

    Talking what is a triangular number ?

    what is a triangular number ????
    badly stuck ...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member vincisonfire's Avatar
    Joined
    Oct 2008
    From
    Sainte-Flavie
    Posts
    469
    Thanks
    2
    Awards
    1

    Reply

    A triangular number is the sum of the n natural numbers from 1 to n. The sequence of triangular numbers for n = 1, 2, 3... is: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ....
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,707
    Thanks
    626
    Hello, sportychick1912!

    What is a triangular number?

    They arise from triangular arrays of objects.
    Code:
                                                  o
                                     o           o o
                          o         o o         o o o
                 o       o o       o o o       o o o o
          o     o o     o o o     o o o o     o o o o o
    
          1      3        6         10           15

    And we have:

    . . \begin{array}{ccccc}T_1 &=& 1 &=& 1 \\<br />
T_2 &=& 1+2 &=& 3 \\ T_3 &=&1+2+3 &=& 6 \\ T_4 &=&1+2+3+4 &=&10 \\ T_5 &=& 1+2+3+4+5 &=&15 \\ \vdots & & \vdots & & \vdots \\<br />
T_n &=& 1+2+3+\hdots+n &=&\dfrac{n(n+1)}{2}\end{array}

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: January 18th 2011, 08:24 PM
  2. triangular matrix
    Posted in the Advanced Algebra Forum
    Replies: 3
    Last Post: May 1st 2009, 06:14 PM
  3. Triangular,squre,pentagonal number
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: April 30th 2009, 12:12 PM
  4. Triangular Pen
    Posted in the Geometry Forum
    Replies: 2
    Last Post: November 16th 2008, 09:41 PM
  5. Triangular \ Square number
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: March 30th 2006, 09:10 PM

Search Tags


/mathhelpforum @mathhelpforum