Urgent algebra!

[Romulus2]

SysOpt has always had a reputation for brilliant brains so I thought I'd try this here. http://sysopt.earthweb.com/forum/smile.gif

The son of a neighbour of mine was given this problem and couldn't solve it. Neither could I and it's been bugging me all night!

What is the algebraic formula for solving the following progression (triangles made up of matchsticks):
<IMG SRC="http://www.romulus2.com/private/match.gif" border=0>
?

I know the next figures will contain 30 and 45 matchsticks respectively but what is the formula???

I'm sure it's incredibly simple for a 12-year-old but unfortunately that was a long time ago for me and my maths is long forgotten! BTW, I won't sleep until I get this - so please help! http://sysopt.earthweb.com/forum/smile.gif

[pickel]

A+ x B-& C+ = 32%( A-B-C) x V1 V2 V3, or was it B+ - C x A- Heck I don't have a clue, this is way over my head. Next time post something EASY!!!! LMOL http://sysopt.earthweb.com/forum/biggrin.gif
Stuff like this gets under your skin, doesn't it ROM ??? http://sysopt.earthweb.com/forum/smile.gif

[superraton01]

easy: 3 9 18 30 45 63 84
. 6 9 12 15 18 21
3 3 3 3 3
SySoPt: after hundreds of posts on
community forum, can i now stop being a JUNIOR member?
pretty please! I promise to agree with
everyone else. I promise to use
VoOgRu ScRiPt FoR aLl FuTuRe PoStInGs!
I pRoMiSe To SoLvE mAtH pRoBlEmS + xPlAiN
wHy YoUr MoThErBoArD wOnT bOoT! I wOnT
mEnTiOn BuSh'S cOcAiNe ArReSt! DoH!
Ps: My AnSwEr Is DiFfIcUlT tO uNdErStAnD
bEcAuSe ThE lEfT mArGiNe WaS aLlIgNeD.
aDd ThE 1St # In LiNe 2 To ThE iSt # In
LiNe 1. ToTaL = 2nD # iN lInE 1, eTc.

[This message has been edited by superraton01 (edited 10-05-2000).]

[Romulus2]

Thank you, superraton01. I got that far (the incremental jumps of 3) but can it be expressed as an algebraic formula? So that by merely entering the length of one side of the triangle into the equation you can calculate the total number of matchsticks in it?

[tonym]

The equation you want is:

T = 1.5 * (N^2 + N), where T = the number of toothpicks and N = the number of rows of triangles.

Tony

[Romulus2]

Yes!!! Thank you! Tony, you're a genius! http://sysopt.earthweb.com/forum/smile.gif

[[hd580]]

Score one for the (Semiconductor/Electrical?) Engineer!