series question (1 Viewer)

[velox]

1,1,1,3,5,9
Write down the nth term
I know the answer. But dont know how to get to it.

thanks

 

[Xayma]

Technically that is a sequence
Anyway I can't see any justifiable pattern.

It goes up by 0,0,2,2,4 but I doubt you could justify that without another term.

 

[velox]

its in the fitz book....It is a sequence, but i had no idea how to get the nth term

 

[Xayma]

Do you have the answer Ill work backwards for you?

Too lazy to go from scratch.

As using the pattern above I get different answers for n being odd/even.

 

[Estel]

heh I see another pattern
Tn= 1 for n = 1, 2, 3.
Tn= Tn-1 + Tn-2 + Tn-3 for n>=4

Can you tell us what section it's in wrx? Might help as to what aspect of sequences we should be looking at...

 

[Xayma]

yeah I was looking at that Estel but I couldnt think of a formula that would work for n=1,2,3.

 

[mojako]

heh I see another pattern
Tn= 1 for n = 1, 2, 3.
Tn= Tn-1 + Tn-2 + Tn-3 for n>=4

Can you tell us what section it's in wrx? Might help as to what aspect of sequences we should be looking at...

actually T(n)= T(n-1) + T(n-2) + T(n-3) for all integers n>=1 if you define the following:
T(-1) = -1
T(-2) = 1
T(-3) = 1


I know I'm not helping haha...

btw for less enthusiastic maths students, this sort of questions is very unlikely to be asked in hsc exams. the syllabus only mentions APs and GPs.

 

[acmilan]

actually T(n)= T(n-1) + T(n-2) + T(n-3) for all integers n>=1 if you define the following:
T(-1) = -1
T(-2) = 1
T(-3) = 1


I know I'm not helping haha...

btw for less enthusiastic maths students, this sort of questions is very unlikely to be asked in hsc exams. the syllabus only mentions APs and GPs.

Its pretty common though to have obscure series questions as q 7 for ext 1 and q 10 for 2 unit, although the may involve arithmetic or geometric series they may not be so obvious