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# Nth term question rather different to normal watch

1. I am a GCSE student doing the intermediate paper. I have a past paper the teacher has given me to do and I am really stuck on one question. The teacher considers me able and so do I because i get 80%-90% all the time.

Anyway here is the question:
Complete the pattern
Pattern Number- 1 2 3 4 5
No. Of Crosses- 1 5 13 25 41

What is the Nth term i have tried all sorts. The differences are 4,8,12,16 so i know for definate it is n squared but what else.

Richard
P.S thanx for any help in advanced
2. The pattern is n^2 + (n-1)^2

For example, if n=3, you get

(3^2) + (2^2) = 9 + 4 = 13

Hope this helps,
Michael
3. (Original post by RuedaNT)
I am a GCSE student doing the intermediate paper. I have a past paper the teacher has given me to do and I am really stuck on one question. The teacher considers me able and so do I because i get 80%-90% all the time.

Anyway here is the question:
Complete the pattern
Pattern Number- 1 2 3 4 5
No. Of Crosses- 1 5 13 25 41

What is the Nth term i have tried all sorts. The differences are 4,8,12,16 so i know for definate it is n squared but what else.

Richard
P.S thanx for any help in advanced
n^2 + (n-1)^2
4. (Original post by RuedaNT)
I am a GCSE student doing the intermediate paper. I have a past paper the teacher has given me to do and I am really stuck on one question. The teacher considers me able and so do I because i get 80%-90% all the time.

Anyway here is the question:
Complete the pattern
Pattern Number- 1 2 3 4 5
No. Of Crosses- 1 5 13 25 41

What is the Nth term i have tried all sorts. The differences are 4,8,12,16 so i know for definate it is n squared but what else.

Richard
P.S thanx for any help in advanced
n^2+(n-1)^2=2n^2-2n+1
5. How do you know that, trial and error?
6. (Original post by mik1a)
How do you know that, trial and error?
well as second difference is same, u know it involves n^2, now see difference between the n^2 value and final value...i noticed that difference between these was a perfect square, which happened to be that of the number below n

wouldnt mind a bit of rep...here and there everybody :-)

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