October 15th, 2011, 08:57 AM  #1 
Newbie Joined: Sep 2011 Posts: 16 Thanks: 0  Arithmetic Series
Hi, was wondering if anyone could help on these questions please? Would be appreciated!! 1) I have the first 3 terms, they are 3, 1, 1 and the common difference is +2. I need to show that n ? (2r5) = n(n4) r=1 2) The first term of an arithmetic sequence is 30 and the common difference is 1.5 It asked me to find the 25th term and I got 300. Then it tells me the rth term of the sequence is 0. * And asks me to find the value of r? Then it tells me the sum of the first n terms of the sequence is Sn. * And asks me to find the largest positive value of Sn? Any help would be great and if possible to show the working out as I have more questions like these. Thanks 
October 15th, 2011, 10:40 AM  #2  
Global Moderator Joined: Nov 2009 From: Northwest Arkansas Posts: 2,766 Thanks: 4  Re: Arithmetic Series Quote:
, where is the nth term, is the first term ( = 3 in this example), and is the difference ( = 2, as you have found) When we plug in the known values, this formula simplifies to . This is, effectively, the summand in the series. But the formula for a finite series is Substitute the known values into this formula and it will match exactly (after simplifying).  

Tags 
arithmetic, series 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
determine arithmetic, geometrical or pseries  Dmath  Calculus  4  March 10th, 2014 01:43 PM 
find the sum of the first 30 terms of this arithmetic series  1love  Algebra  10  May 20th, 2012 11:32 PM 
Arithmetic Series  poochie03  Algebra  1  November 6th, 2011 02:10 PM 
Sum of arithmetic series...  lgchic  Applied Math  1  April 3rd, 2008 06:11 AM 
find the sum of the first 30 terms of this arithmetic series  1love  Calculus  2  December 31st, 1969 04:00 PM 