 If You're Good At Maths..., I have a sequence problem |
|
|
|
|
  |
 Jan 14 2008, 09:42 PM
Post
#1
|
|
|
Advanced Member  Group: Members Posts: 104 Joined: 8-September 06 From: London Member No.: 29,637  |
Well, for GCSE, our teacher gave us this sequence and told us to find the nth term. Well, unsurprisingly, he did not tell us how to do it. Thats just what he's like.
So, I decided to post here for help, because we have some intellectual people here =] So, the sequence is--> 11, 44, 110, 220, 385 1st difference --> 33, 66, 110, 165 2nd difference --> 33, 44, 55 3rd difference --> 10, 10 |
 |
 
|
|
Jan 14 2008, 10:10 PM
Post
#2
|
|
|
Premium Member Group: Members Posts: 162 Joined: 18-July 06 Member No.: 26,797 |
http://answers.yahoo.com/question/index?qi...13024836AAFyEPv
from what I can tell the equation to find the nth term would be: 11/6(n^3) + 11(n^2) + 121/6(n) + 11 = nth term |
|
|
|
|
Jan 14 2008, 10:13 PM
Post
#3
|
|
|
Member [Level 3] Group: [HOSTED] Posts: 92 Joined: 1-January 08 Member No.: 55,554 |
Hello,
the ninth term is 1815. the full sequence it: 11,44,110,220,385,616,924,1320,1815 1st difference --> 33,66,110,165,231,308,396,495 2nd difference --> 33,44,55,66,77,88,99 3rd difference --> 10,10,10,10,10,10 |
|
|
|
|
Jan 14 2008, 10:18 PM
Post
#4
|
|
|
Advanced Member Group: Members Posts: 104 Joined: 8-September 06 From: London Member No.: 29,637 |
I LOVE YOU GUYS!!
Thanks DarkPsycho and I really hope demonlord was joking!! 
|
|
|
|
|
Jan 14 2008, 10:37 PM
Post
#5
|
|
|
Premium Member Group: Members Posts: 162 Joined: 18-July 06 Member No.: 26,797 |
No problem
 Just a little Google Search did the trick. 
|
|
|
|
|
Jan 16 2008, 12:16 AM
Post
#6
|
|
|
Member [Level 1] Group: Members Posts: 57 Joined: 15-January 08 From: The Fork Draw Member No.: 56,309 |
ZOMG! I cant read that ... you must be like geniuses .. LOLOL
|
|
|
|
|
Jan 19 2008, 08:09 PM
Post
#7
|
|
|
Advanced Member Group: Members Posts: 104 Joined: 8-September 06 From: London Member No.: 29,637 |
Lol, well I still had to learn how to find the nth term of a cubic sequence, so there wasn't much point in copying anyway.
Me and my friend discussed it over break-time, and we figured it out. It took about 4 A4 sized papers though lol =] (even though the above equation was correct, google searches are usually junk) |
|
|
|
|
Jan 26 2008, 04:41 PM
Post
#8
|
|
|
Super Member Group: [HOSTED] Posts: 416 Joined: 26-January 08 Member No.: 56,881 |
Then again, if you divide all the terms by 11, you get something from Pascal's Triangle:
11, 44, 110, 220, 385, ... becomes 1, 4, 10, 20, 35, ... which would break down into the first, second, and third differences as demonlord described, only divided by 11. Only, isn't the third difference 11 instead of 10? |
|
|
|
|
Similar Topics
| Topics | Topics | |
|---|---|---|
|
|
|
|