xisto Community

# If You're Good At Maths... I have a sequence problem

## Recommended Posts

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, 3851st difference --> 33, 66, 110, 1652nd difference --> 33, 44, 553rd difference --> 10, 10

##### Share on other sites

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

##### Share on other sites

Hello, the ninth term is 1815.the full sequence it:11,44,110,220,385,616,924,1320,18151st difference --> 33,66,110,165,231,308,396,4952nd difference --> 33,44,55,66,77,88,993rd difference --> 10,10,10,10,10,10

##### Share on other sites

I LOVE YOU GUYS!!Thanks DarkPsycho and I really hope demonlord was joking!!

##### Share on other sites

No problem :)Just a little Google Search did the trick.

##### Share on other sites

ZOMG! I cant read that ... you must be like geniuses .. LOLOL

##### Share on other sites

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)

##### Share on other sites

Then again, if you divide all the terms by 11, you get something from Pascal's Triangle:11, 44, 110, 220, 385, ...becomes1, 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?

## Create an account

Register a new account