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Learning sequences and series.

1.Find the sum of the first 5 terms given.
t1= 2b-1 , t2=3b+2, t3=5b+3

2. Find the 32nd term given: -5,8,-11,7

April 29, 2015

6 Comments • Newest first

RoyaIBIue

@gamemage3: you know, I actually found a pattern but (as I previously stated) it had totally nothing to do with arithmetic/geometric series.
1 ) t2 = t1 + (b+3) then t3 = t2 + (2b+1) which suggests that t4 = t3 + (3b-1) and t5 = t4 + (4b-3) , then you just add.
2 ) -5,8,-11,7 , at the beginning this "sequence" looks like just a set of random integers, but then after some observation I figured that U1 (i use "U" to represent the term) and U3 have something to do with each other and also U2 and U4 from there I figured that U4= U2-1 and if you continue with that then U32 = U4 -14 ( there are 14 even terms between U4 and U32), which gives an answer of -7, but well, I don't have enough data to say that my interpretation is correct so it's possible that I didn't reach to the correct conclusion.

Reply April 30, 2015 - edited
gamemage3

sequences are arbitrary

i can go 1,2,3,4, then 10000 and eventually it could be a pattern

you didn't say if it its arithmetic or geometric, and it seems like neither

so the answer im going to give an answer as E100#^#^#^#^#^#^#^#^#100b + 200![200([200(200)200])200] for the first one

and {L100,10}10,10

Reply April 29, 2015 - edited
RoyaIBIue

@LastPhantomHero : It's very likely that it is neither ( at least for question 2 ) .. no common difference, no common ratio...

Reply April 29, 2015 - edited
LastPhantomHero

You really need to mention whether it is geometric or algebraic. Answers vary depending on the info.

Reply April 29, 2015 - edited
RoyaIBIue

I'm not entirely sure of what I got, but these are my answers anyway:
1) Sum = 30b + 5
2) 32nd term = -7

I have to add though, if my answers are correct then those 2 questions had totally nothing to do with arithmetic/geometric series/sequences, so it's a total waste of time to try using the arithmetic/geometric formulas to solve these problems.

Reply April 29, 2015 - edited
Ness

Your question is incredibly vague.

Reply April 29, 2015 - edited