Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
Yahoo!
Group Title
Find the n th term and sum of n terms of the series 5 + 8 + 17 + 44 ..........
 2 years ago
 2 years ago
Yahoo! Group Title
Find the n th term and sum of n terms of the series 5 + 8 + 17 + 44 ..........
 2 years ago
 2 years ago

This Question is Closed

dpflan Group TitleBest ResponseYou've already chosen the best response.1
Ah, this is a nice series. \[[5,8,17,44]\]
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
find the difference .. note the difference in the difference is a multiple of 3
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
Yes the first order difference is in Gp
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
and on...so do as @experimentX suggests, first examine any sort of relationship that could exist, you see that each termer is greater than the next
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
I suggest that you show us the values you have for the difference between the numbers in the series
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
Once, you have those differences, see if there is a pattern or relationship among them
 2 years ago

zepp Group TitleBest ResponseYou've already chosen the best response.0
Looks like 3 to some power :D
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
tn+1 = tn + 3^(n1)
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
term1 = 5 term2 = 8 term2  term1 = 3 so term2 = term1 + 3 term3 = 17 term3  term2 = 9 so term3 = term2 + 9 term4 = 44 term5  term4 = 27 so term4 = term3 + 27 term5 = ...
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
don't know closed form at the moment!!
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
So @Yahoo! How are you doing with this?
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
Ar^n + b1n^k1 + b2n^k2............bk
 2 years ago

dpflan Group TitleBest ResponseYou've already chosen the best response.1
Hmm, can you explain the terms please?
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
it is the general formula lol1
 2 years ago

sami21 Group TitleBest ResponseYou've already chosen the best response.0
ok look at the sequence first term is (3^1+7)/2=5 second is (3^2+7)/2=8 third is (3^3+8)/2=17 can you now tell me general formula ?
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
i guess we should use summation rule dw:1343147827410:dw
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
dw:1343147906405:dw
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
dw:1343147929358:dw
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
not sure that works!
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
dw:1343147968035:dw something like that!! just try to manipulate and fit in it ...
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
dw:1343147962155:dw
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
dw:1343148038487:dw
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
dw:1343148023475:dw
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.0
i like to get the first term to 1 alot of times 5 + 8 + 17 + 44 4 4 4 4  1 + 4 + 13 + 40 just helps me with the inbetween addings or if we up it by +1 5 + 8 + 17 + 44 +1 +1 +1 +1  6 + 9 + 18 + 45
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.0
factor out a 3 3( 2 + 3 + 6 + 15 + ...) all ways to se it differently
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
dw:1343148174027:dw
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
i hope it works for other terms too .. let's see for sum
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
@experimentX i didnt understand!!
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
dw:1343148311125:dw
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
that's just some manipulation .. typing in latex really takes lot of time
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
\[ t_n = t_{n1} + 3^{n1}\] this is the general rule \[ t_{n} = t_{n2} + 3^{n 2} + 3^{n1} \] continue this way and you will get \[ t_{n} = t_1 + 3 + 3^3 + 3^4+ .. + 3^{n 2} + 3^{n1} = 5 + 3{ 3^{n1}  1 \over 31}\] which is requited formula
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
for summation \[ \sum_{n=1}^k {5 + {3 \over 2} (3^{n  1 }  1)} =\sum_{n=1}^k{7/2} + 3^n = k {7 \over 2}+ 3{3^k 1 \over 31} = k {7 \over 2}+ {3 \over 2}(3^k 1)\] @Yahoo! do you understand??
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
dw:1343149457407:dw
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
@experimentX I guess you missed 1/2 .
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
thanks @mahmit2012 for correction ... you are sharp!!ii
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
@mahmit2012 @experimentX i learnt this by using this Ar^n + b1n^k1 + b2n^k2............bk
 2 years ago

mahmit2012 Group TitleBest ResponseYou've already chosen the best response.1
You're welcome , and good tutoring you have had. @experimentX
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
Ar^n + b1n^k1 + b2n^k2............bk
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.0
can u ssolve this by using Ar^n + b1n^k1 + b2n^k2............bk
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.2
you are a good tutor!! most of me is autodidact!!
 2 years ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.